Triumph Rat Motorcycle Forums banner

1 - 20 of 36 Posts

·
Registered
Joined
·
26 Posts
Discussion Starter #1 (Edited)
Hey Guys,

Finally got the bike back together and running good enough, however there is still an issues I am tracking down.
With an single AMAL 930 premier carb and #19 pilot

I am trying to tune the carb spitting that occurs from idle with a quick snap of the throttle. Sometime's it flames out, other times if i release the throttle it will stay running. While moving the bike rips, no spitting or anything that I can tell. Yet, once i stop and give it a blip before taking off again it will spit. If i check the plugs from idling they look slightly rich. Which tells me my carb settings are decent enough and not lean on the idle circuit. Yet, spitting is said to be from a lean condition. Any time I open the throttle with ease the bike runs like a champ.

I'm curious if this is normal, or if there is something I need to look at next. I checked for air leaks around the carb, and didn't find any with a butane torch.

My valve's were checked and theyre set correctly.

I have not checked the ignition timing, if i start down that rabbit hole im probably going to go with a boyer system(if anyone has the correct system i would appreciate that info too)

Otherwise, the bike idles nicely and rides great... which makes this tough because i dont want to make anything worse.

Hoping that someone else might have had a similar issue..

Thanks
 

·
Registered
Joined
·
5,462 Posts
Sorry, but retarded timing will cause the carb to spit, so it’s one thing to check.
Wrong slide cutaway or leakage around the slide can cause it.
Advance unit not functioning correctly can cause it.
A valve leaking might cause it to spit .
Is a #19 pilot normal for your bike ?
Are you running mufflers ? Air filters ?
If your cutaway or pilot is leaner than what is normal , I’d suggest trying what others use with the same bike.
 

·
Registered
Joined
·
1,295 Posts
There’s no point trying to tune it to run better while refusing to check ignition timing, points gap and other service items.
 

·
Registered
Joined
·
137 Posts
FWIW the last 3 reuilds I have done have needed 1/2 smaller slide cutaway to get rid of hesitancy coming off tickover, and that with new concentrics. I guess you are running the standard 3 1/2 now, I'd go down to a 3. Fuel is very different now than back in the day (even though different again from UK to USA)
HTH
Mick
 

·
Registered
Joined
·
3,429 Posts
Hi Jackdawack, Where do you live? Fuel can make huge difference. As Mick found I also find Tigers tend to like #3 slide better. The can also prefer .1065 needle jet. Amal sells this special size.

Overall E10 Unleaded fuel in USA, motor likes about 5% richer jetting across the board.

You have premier. Good! They work great. .019 pilot (idle) jet is correct & works better than .017 like old carb had. Many internal changes in premier so they require different settings.

Float setting for premier is very different. Just above gasket surface & level. This is correct! If you lowered float level, raise it back up. then road test before moving on.

As was stated, timing is critical. It must be checked. You may find bike works better 3/32" retarded. I'd do that. I do that on my bike as well as others I tune. Looking at pointer in timing cover. Hash mark on rotor will end up 3/32" closer to front wheel from pointer.

On occasion the rotor alloy can slip on the steel center hub. That will throw timing marks off. Good plan to verify the rotor hash & pointer with TDC tool in 38b slot in flywheel. Note position & compensate with the hash/pointer relationship. Timing is very important. Even left to right is important.

Well serviced points are very reliable & allow starting with dead battery. Key work: Well serviced. Taking half a turn of end of advance spring & smoothing any flat spot worn in fly weights is good idea. Smooths idle & just above idle.

On the other hand, Boyer has a much more desirable advance curve. Gives perfect timing left to right. Tends to reduce the shake in motor just off idle that points AAU may cause. The down side of Boyer or any other electronic ignition is low voltage will make impossible or hard to start. So if you choose electronic be sure your battery & charging system is always well maintained & electrical output is to specs. In every case poor charging system is no good, so in many owner's mind, electronics advantages far out weigh the negative of low volts. The single biggest advantage of electronic ignition is the desirable advance curve with modern fuel. Substantially reduces pinging & holed pistons, but if mixture or timing is not properly set it cannot compensate for that.

Regarding getting slide & all the other mixtures correct, it will take some practice, experiments & very important to mark your grip in 1/8s. Use masking tape on grip & throttle housing. Take up cable slack very gently, twisting grip. Mark that zero. Turn to full throttle. Verify slide is full up. Mark as full. Then divide marks in halves. The eye can find center points fairly well. Use dividers if/as needed. Be accurate on marks! Adjust throttle cable, idle rpm as needed before marking grip.

Often needle will want full up, meaning clip on bottom groove. Main jet one size lower than 8 stroking. This will go a long way in preventing melted pistons on hot days up hills. Remember unlead fuel plug readings are really tricky. Not like '60s & '70s. When it looks a little too rich is probably just right. However, go more by road tests than plug reading.

You'll soon learn how little throttle is used. Seldom more than 1/16-1/8. The needle will wear flat spot here. That skew mixture into being rich at worn point. So watch out for that. If you lean it there to just right, it defaults to lean when jet is on unworn part of needle. If in doubt replace needle & needle jet. Jet wears oval. Even .0005" wear is a decided change in mixture. Sometimes.... a worn jet with new needle is just right. Trial & error. Try each one & see.

Again, worn needle is always problematic.

Slide size is found at snap throttle test. Sometimes (often??) you'll be right between #3 & 3-1/2 cutaway. Default to richer #3 if you find this.

Since bike runs good you're not far off. Start with main jet then work with needle clip, then slide. Your pilot get of .019 is good. It will have 3 small rings machined into the silver tip of jet.

Print the road test part of John Healy's tuning guide. Put it in your pocket, you'll need to memorize it.

8 stroking is an odd misfire that sounds like ah ah ah ah ah at full or just shy of full throttle. Backing off goes away. cranking on comes back. High gear 65 mph up a moderate hill or head wind is easiest.

To rich if slide can 8 stroke on snap throttle. But you need to really listen & know what 8 stroke sounds/feels like.

Too lean the bike will gain very slight power when you back off throttle, like 1/32 turn. Very hard to feel until you understand it. Easy to smoke piston when lean. Better to go too rich, then back off going leaner a little at a time.

Again start with main jet. If main jet is not right, it can/will confuse the needle clip position.

I don't know what air filter or exhaust you are using. That will make a difference in mixture.

I've chased my tail for days (a few months actually) with paper elements in air filter. Don't use them. The original type wire/gauze is better. They clean fine & don't mess with air flow at different RPM. Or should I say, Triumph must have designed carbs to complement them.

Find a road test route that has all the conditions of testing you need. Use same route every time. Then you'll feel changes much more readily. It takes a good 10-15 miles to get motor/carb to minimum temp to set mixtures. After 50-60 miles you may need to trim idle mixture idle rpm. You'll learn to find the happy medium.

There is no provision for cold fast idle, so motor will not idle on cold mornings & in hot weather take a good 2-3 miles before idle is to be trusted. If bike runs really well cold, idle mixture is too rich. Some Electronic ignition has idle stabilization by changing idle timing. They idle great no matter what unless really cold like <40f. That's another story.

What sucks about our bikes is you must remove carb to access slide. Makes the job very time consuming. Just have to accept that. If you have stock air filter, the boot is a pain. 750 Tiger is worse with offset boot hole.

Here's the tuning guide. NOTE the float level of .080" is for older carbs, NOT premier. They demand much higher to achieve the correct liquid level in bowl.


Don
 

·
Registered
Joined
·
26 Posts
Discussion Starter #6
FWIW the last 3 reuilds I have done have needed 1/2 smaller slide cutaway to get rid of hesitancy coming off tickover, and that with new concentrics. I guess you are running the standard 3 1/2 now, I'd go down to a 3. Fuel is very different now than back in the day (even though different again from UK to USA)
HTH
Mick
Yes, the "correct" size was the 3 1/2" for my model. I will consider this as an option once I go through the ignition timing and everything else.

Hi Jackdawack, Where do you live? Fuel can make huge difference. As Mick found I also find Tigers tend to like #3 slide better. The can also prefer .1065 needle jet. Amal sells this special size.

Overall E10 Unleaded fuel in USA, motor likes about 5% richer jetting across the board.

You have premier. Good! They work great. .019 pilot (idle) jet is correct & works better than .017 like old carb had. Many internal changes in premier so they require different settings.

Float setting for premier is very different. Just above gasket surface & level. This is correct! If you lowered float level, raise it back up. then road test before moving on.

As was stated, timing is critical. It must be checked. You may find bike works better 3/32" retarded. I'd do that. I do that on my bike as well as others I tune. Looking at pointer in timing cover. Hash mark on rotor will end up 3/32" closer to front wheel from pointer.

On occasion the rotor alloy can slip on the steel center hub. That will throw timing marks off. Good plan to verify the rotor hash & pointer with TDC tool in 38b slot in flywheel. Note position & compensate with the hash/pointer relationship. Timing is very important. Even left to right is important.

Well serviced points are very reliable & allow starting with dead battery. Key work: Well serviced. Taking half a turn of end of advance spring & smoothing any flat spot worn in fly weights is good idea. Smooths idle & just above idle.

On the other hand, Boyer has a much more desirable advance curve. Gives perfect timing left to right. Tends to reduce the shake in motor just off idle that points AAU may cause. The down side of Boyer or any other electronic ignition is low voltage will make impossible or hard to start. So if you choose electronic be sure your battery & charging system is always well maintained & electrical output is to specs. In every case poor charging system is no good, so in many owner's mind, electronics advantages far out weigh the negative of low volts. The single biggest advantage of electronic ignition is the desirable advance curve with modern fuel. Substantially reduces pinging & holed pistons, but if mixture or timing is not properly set it cannot compensate for that.

Regarding getting slide & all the other mixtures correct, it will take some practice, experiments & very important to mark your grip in 1/8s. Use masking tape on grip & throttle housing. Take up cable slack very gently, twisting grip. Mark that zero. Turn to full throttle. Verify slide is full up. Mark as full. Then divide marks in halves. The eye can find center points fairly well. Use dividers if/as needed. Be accurate on marks! Adjust throttle cable, idle rpm as needed before marking grip.

Often needle will want full up, meaning clip on bottom groove. Main jet one size lower than 8 stroking. This will go a long way in preventing melted pistons on hot days up hills. Remember unlead fuel plug readings are really tricky. Not like '60s & '70s. When it looks a little too rich is probably just right. However, go more by road tests than plug reading.

You'll soon learn how little throttle is used. Seldom more than 1/16-1/8. The needle will wear flat spot here. That skew mixture into being rich at worn point. So watch out for that. If you lean it there to just right, it defaults to lean when jet is on unworn part of needle. If in doubt replace needle & needle jet. Jet wears oval. Even .0005" wear is a decided change in mixture. Sometimes.... a worn jet with new needle is just right. Trial & error. Try each one & see.

Again, worn needle is always problematic.

Slide size is found at snap throttle test. Sometimes (often??) you'll be right between #3 & 3-1/2 cutaway. Default to richer #3 if you find this.

Since bike runs good you're not far off. Start with main jet then work with needle clip, then slide. Your pilot get of .019 is good. It will have 3 small rings machined into the silver tip of jet.

Print the road test part of John Healy's tuning guide. Put it in your pocket, you'll need to memorize it.

8 stroking is an odd misfire that sounds like ah ah ah ah ah at full or just shy of full throttle. Backing off goes away. cranking on comes back. High gear 65 mph up a moderate hill or head wind is easiest.

To rich if slide can 8 stroke on snap throttle. But you need to really listen & know what 8 stroke sounds/feels like.

Too lean the bike will gain very slight power when you back off throttle, like 1/32 turn. Very hard to feel until you understand it. Easy to smoke piston when lean. Better to go too rich, then back off going leaner a little at a time.

Again start with main jet. If main jet is not right, it can/will confuse the needle clip position.

I don't know what air filter or exhaust you are using. That will make a difference in mixture.

I've chased my tail for days (a few months actually) with paper elements in air filter. Don't use them. The original type wire/gauze is better. They clean fine & don't mess with air flow at different RPM. Or should I say, Triumph must have designed carbs to complement them.

Find a road test route that has all the conditions of testing you need. Use same route every time. Then you'll feel changes much more readily. It takes a good 10-15 miles to get motor/carb to minimum temp to set mixtures. After 50-60 miles you may need to trim idle mixture idle rpm. You'll learn to find the happy medium.

There is no provision for cold fast idle, so motor will not idle on cold mornings & in hot weather take a good 2-3 miles before idle is to be trusted. If bike runs really well cold, idle mixture is too rich. Some Electronic ignition has idle stabilization by changing idle timing. They idle great no matter what unless really cold like <40f. That's another story.

What sucks about our bikes is you must remove carb to access slide. Makes the job very time consuming. Just have to accept that. If you have stock air filter, the boot is a pain. 750 Tiger is worse with offset boot hole.

Here's the tuning guide. NOTE the float level of .080" is for older carbs, NOT premier. They demand much higher to achieve the correct liquid level in bowl.


Don
I am in Northern New Jersey.
If anyone knows a specialist in the area I am interested since my time is limited right now.

Thats really funny!!! I did in fact lower the float bowl and it did come set above the gasket.
Yes, I have had to remove and re-install the carb probably 4 times already and with the 2 stock airboxes it has to be the biggest pain in the arse. I will reset the float level and then move on.

Next.
I am going to see if i can sort out the timing and check to make sure it is set correctly. I have the TDS flywheel tool because I knew i was going to have to deal with this at some point. I am a bit worried about screwing this step up, but I will make all my measurements before taking anything apart.

From there I will work through everyones suggestions.
 

·
Registered
Joined
·
3,429 Posts
Hi Jack, Put your mind at ease. The procedures are not hard. Just takes a little practice. I'll send you a cheat sheet tonight after 10pm pacific time tonight.

You will not screw this up, trust me!

Good to have a spare gasket on hand for the access cover with the 3 screws. The gasket will sometimes tear on removal.

You must have a timing light of course. A separate 12v battery to power the light. Spare bike battery or park you car close enough. Or remove car battery. Also a box fan placed in front of bike is a very good idea. Motor will get quite hot without fan during setting. NEVER power timing light from bike's battery. Some timing lights have internal battery (mine does) so it's self powered. In that case you don't need extra battery.

You'll also need feeler gauges .014, .015, .016". Easier to set points.

Some very fine sand paper/emery paper, or wet or dry paper, or fine thin emery board to file points if/as needed or dedicated points file or points emery board.

Tube of Lubricam SL2 points cam lube. May find local, ebay has it. Points lube is a must!

Don't mess with timing until you have items needed to do good job. Resetting float level will change things. Luckily the bowl is easy to remove.
Don
 

·
Registered
Joined
·
26 Posts
Discussion Starter #8 (Edited)
I raised the float bowl, didn't do much of anything. Still wants to flame out if i crack the throttle quickly. I will consider purchasing a Boyer system after reviewing some more info on the timing procedures on the stock unit. I would need a timing light and the point lube, should have everything else. I might look for a #3 slide as well.
 

·
Registered
Joined
·
368 Posts
jack, just learn how to check the timing.

its a five minute job and takes zero brains.

youll need a timing light anyway if you want to keep the bike.

points are another ten minutes.

these things require 1930s technology. dont overthink it.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #10
Gonna order the light tonight, and if I get an hour Im gonna put the original carb back in and see tomorrow if the issue changes. This way I can isolate the carb. The original was rebuilt anyway prior to getting the premier, I just liked the idea of putting the premier on. If the problem disappears I will go down that hole of a new 3# slide etc. I will check the timing regardles, and It would be a nice skill to add to the basket.
 

·
Registered
Joined
·
3,429 Posts
Hi Jack, Just get an inexpensive simple timing light. No need for fancy degree reading or the like. No need for RPM reading. You only need those features for getting into special timing curve tuning or advance unit diagnosis.

Start by looking at points wires. Black/white wire goes to front set of points. Look at coils. Black/white should go to left coil.
Black/yellow wire goes to rear points. Looking at coil, it should go to right coil. This is the factory way it was done. Notice the black/yellow wire is longer to reach to the rear points.

The power wire to coils is white/yellow. Notice it connects to one coil, then goes to the other. We won't think about this wire. Just so you know what it is though.

Look at screws on points plate(s). The pillar bolts allow the entire assembly to rotate. The screw on points allows points to adjust. Notice the eccentric screw in the slot. You rotate it to change point gap. One way wider, the other closer. Practice that... Notice you must loosen points screw a little to allow points to move freely, but not too much. All 4 eccentric screws are very weak/flimsy. If you force it at all it will break or strip slot. So practice how much to back off points screw to get eccentric screw to move things. Just takes a little practice to get this right.

Now move to sub plates. They are secured by the screws that hold the lube felt bracket. As you can see there are 4 screws total. 2 for each side. Obviously you loosen screws on side you want to adjust. However sometimes you need to loosen the other 2 slightly to relieve tension on the bracket. Again practice moving the sub plates using eccentric screws. Notice how the sub plates move in arc. Make a cheat sheet so you know which way to turn eccentric to move sub plate the direction you want it to move. The sub plates allow you to set timing on left & right sides individually.

File tit off point face if they have one. Clean off any filing dust 100% if any dust is left behind it will wear cam & rubbing block. Again folding emery paper or wet/dry about 400 grit. Wet or dry works quite well used dry.

Set rubbing block to hash mark. Gap points. Rotate motor. Gap 2nd set. No matter which set you do first. I start with right set just because I do.

To gap points use .014" & .016" feeler gauge. .014 will feel sloppy. .016 will feel snug. Don't really need .015, but fun to see how it feels.

Clean point faces well with strips of copy paper using alcohol, parts wash, or gasoline. Dry with dry strip of paper. Clean until paper comes out clean. Again verify not a trace of sanding dust on rubbing block or cam.

Place a very thin smear of points lube on cam. Place dab of grease size of paper match head on rubbing blocks. You see my grease is green. Lubricam is brownish. Put only one drop of motor oil on felt lube pads if they are still there. Not there, no matter. Grease alone will work perfectly. Do not forget the grease! Notice side of rubbing block grease is on. this way rotation pulls grease onto cam.

Mark the points sub plate with marker pen L & R so you don't forget which points is for which side of motor.

Now you are ready to set timing. Remove cover on primary cover. Hook up timing light to left cylinder (spark plug wire). Turn on fan to cool motor.

Start motor, rev motor to approx. 3500-4000 or until you see hash mark on rotor stop advancing. Very easy to see this. Idle it's not near pointer at all. Rev motor & it moves right around to pointer area. When mark lines up with pointer at above RPM it's 38B, which is spec.

If hash mark doesn't line up look at cheat sheet. Move points sub plate according to cheat sheet until hash mark lines up to pointer. Once you have the left side timed, you'll move to right cyl.

Move timing light to right cyl spark plug wire. Star motor, rev it as before. Adjust the left points sub plate as you did for they other cyl until hash mark lines up with pointer. Remember this time, you'll move the left point sub plate.

Once this side lines up with pointer your done. Both sides are now timed.

That is done. Disconnect timing light, install covers for primary & points.

If you hear pinging you can retard the timing, but when you are learning just use the 38B mark.

Since you are still learning it will take some time. Budget a few hours. Once practiced it takes 10 min. But not when you are figuring all this out.

There is a lot of oil flying around in primary. It is messy job & expect oil to blow out when you start & run motor. Consider putting cardboard on floor. About 3x3' sheet.

You can make a plastic window for opening screwed in place of cover to get no mess. It will condensate bad for a few minutes until it heats up. That's another subject. Just deal with mess for now.

Looking at pic of my points you can see the grease. Don't confuse hash mark with the large square slot. Put rubbing block on hash mark, not slot when setting gap.
Don
 

Attachments

·
Registered
Joined
·
3,429 Posts
Timing similar to this on eBay is good enough. The pickups for plug wire are quite fragile to shock. Don't drop them. Zip tie wire away from heat. Try to keep pickup off fins so it doesn't vibrate pick up.


Many of these lights are not very durable. Even the costly ones aren't much better (often worse). Bulb in the light is fragile also. So be gentle with any of them. You want one that says good to about 7-10000 rpm max. The really cheap ones cut out at the higher rpm that we need to set our timing. They crap out around 2000 or less!
Don
 

·
Registered
Joined
·
26 Posts
Discussion Starter #13
Timing light came yesterday, new battery today. Waiting on the gasket for the inspection cover and will work through getting all the timing checked and adjusted if necessary. I went with a slightly costly light 100 bucks due to a lot complaints I read about them being cheap, came witha nice storage case too. Unfortunately, a lot of deliveries lately are coming damaged, and in soft packaging. So I opted for something a bit more durable.

I ordered a spotting scope for my shooting hobby, 500 bucks and they slapped a shipping label on the product box and just shipped it in original packaging. Needless to say the box was crushed becuase it was never designed to be shipped like that.

Anyway I will read through all the above and report back.

Thanks for all the help.
 

·
Registered
Joined
·
368 Posts
i uze a simple dial back to zero light for timing everything. ignition timing makez a big difference in how well your motor works, and if your elevation or fuel grade isnt the same as it wz when and where your bike was made (and it wont be), you can make it run better by advancing or retarding the spark a bit from the factory setting. i have TDC marked on my front pulley and i can set to any number i want to try.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #15
Ok so, I started messing with the points and actually opted for a static timing set up before strobe checking and fine tuning.

I set the points gap, that was easy enough. However, when I went to auto advance the timing something seemed odd.

The "brass" cam with the scribe mark on it. I can rotate it about 20 degrees(just a guess) forward and back with zero effort, and it will stay in what ever position I leave it. Am I correct that there should be a spring behind the points unit that holds it in place? Shouldn't it spring back from the auto advanced positon?

I have not removed the plates yet, it was like 1am when I discovered this last night, but wanted to get an opinion before I went back out tonight.

If i end up pulling the entire ignition system out im gonna put a damn boyer in.
 

·
Registered
Joined
·
512 Posts
Am I correct that there should be a spring behind the points unit that holds it in place? Shouldn't it spring back from the auto advanced positon?
Yes it should spring back. There should be two weights which move outwards against their respective springs as the revs rise, when the revs drop the springs pull the weights back in retarding the ignition.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #17
Yes it should spring back. There should be two weights which move outwards against their respective springs as the revs rise, when the revs drop the springs pull the weights back in retarding the ignition.
Thats what i thought, I will pull the timing unit out and check.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #18
I pulled the timing unit out. The cam now rotates into auto advance, and will spring back on its own.

First off, is there a way to clean the auto advanced assembly with out removing it? To remove it do i just pull the cam bolt out? The entire assemby feels sticky like bearing grease.

Second, the springs for the unit feel "weak" im not sure how much tension there should be, but the weights move outward with minimal effort. Is this normal? If I put a flat head in the cam notch it takes zero effort to push it into the advanced positon. I have s feeling its normal but just want to check.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #19
I cleaned out the auto advance so it looks like its moving freely and resetting under spring tension. My next issue: I have the flywheel locked at 38BTDC, and this is the most adjustment I can get out of the points.
Any advice?
 

Attachments

·
Registered
Joined
·
26 Posts
Discussion Starter #20
Actually I'm not supposed to line up that hash at 38btdc? I'm just supposed to set the point gap to .015 using the secondary plate adjustment?
 
1 - 20 of 36 Posts
Top