Triumph Rat Motorcycle Forums banner

1 - 18 of 18 Posts

·
Registered
Joined
·
209 Posts
Discussion Starter #1
Apologies if this is covered elsewhere, but I couldn't find it.

The choke lever on my 73 Tiger 750 is mounted on the lhs air box - where it should be. The stock choke cable is about a foot long. Last year I had it running from the lever to the TS, under the spine tube, then up and over and into the top of the carb. It worked, just, but it's horrible.

I can't find any pictures, diagrams or description of where the single choke cable is supposed to run from the lever to the carb (single carb remember!)

Could anyone help me out pls? Can't believe Triumph routed that cable where I had it last year. There has to be a better route (like putting a lever on the handlebars and doing it properly!) than the one I worked out.

Thx

Andy
 

·
Registered
Joined
·
209 Posts
Discussion Starter #3
Hi Chris, It's only 2 small 1/8 or 2BA holes and I'd simply put a stainless dome head bolt in there. But I'd prefer to have it as Triumph intended! More than one way of skinning the cat though!
 

·
Premium Member
Joined
·
9,529 Posts
My 79 bonnie has the choke on the bars.
Imho a far more sensible location
I have mk2 carbs but the TR7 also had a choke there with a mark1. You can get cables with elbows at the carb end
 

·
Registered
Joined
·
2,923 Posts
Hi Andy, I'll take some photos of mine. It is correct from new. Might be Monday your time by time I post them. The factory routing is simple & works good. Slightly in way of tickler, but not bad at all. I don't mind the lever on side of air box. However it's easier to forget to turn off choke since you can't see it. What I don't like about bar mounted lever, in a collision it can dig into your body as you go over bars. I'd want choke off to have lever pointing forwards. I think about these things. You never know what can happen....
Don
 

·
Registered
Joined
·
209 Posts
Discussion Starter #6
Hi Don,

I knew you'd know! Many thx. No rush. Awaiting new wedding bands (mine are a bit loose) so head not going back on for a few days. Working on primary side atm.

And yes, I forget the choke as well, until I wonder why it's coughing!

Andy
 

·
Registered
Joined
·
209 Posts
Discussion Starter #8
Many thx Don. That's very nearly the routing I worked out last year, but I always found it stiff and so I thought it must be wrong. I'll lube up the cable and see if that makes a difference too. I'll put it back exactly how you have it and see if that's better.

Why the spring across the airbox halves? Mine's got 2 small bolts inside the airbox, top and bottom of the air intake opening, and no bolt holes for the spring anchors.
 

·
Premium Member
Joined
·
9,529 Posts
The fibreglass covers hook around the rear diagonal and then are held together at the front top and bottom by springs.
 

·
Registered
Joined
·
209 Posts
Discussion Starter #10
Ah, OK, thx Dave. My airboxes are aluminium, so maybe they don't need the spring as they bolt together.
 

·
Registered
Joined
·
2,923 Posts
Hi Andy, The routing of the cable is not ideal. The fat back bone doesn't allow gradual bend from top of car. Still better than many earlier Bonnies where there is no room at all under rear of fuel tank. Triumph just did what they did and we get to figure a way to make it work best we can.

Yes the cable should be lubed. I just use motor oil. Seems to work fine. Cable lube might be better. Also the lever tension is adjustable with the screw. Takes a little experimenting if you're going for easy movement. Too loose & lever will vibrate to nearly full choke. I just leave mine fairly stiff to prevent that. If screw won't hold adjustment a drop of blue Loctite 272 works well. I ended up doing that.

Regarding the springs, my plastic covers warped such that the front edges had quite a gap. Easily 3/16"+. Obvioulsy this allows lots of unfiltered are in. Plus... And this is imporant a backfire into air box can lead to bike fire. A flame cannot redily pass through air filter element especially the screen. I had gotten my bike from 34 years storage & had the original plastic float & needle. The air box had the large gap. One night after work I had to start bike in dark & on a slope. Gave it a tickle & kicked it. Backfired through air filter, gas had ran out of carb & into housing which is common. But it also ran out of bottom of air filter. Anyway started fire inside air box & down left side of bike. Not too bad though. I kicked hard to suck flames in & that helped. Then I blew remainder of flames out... Actually God put the fire out. That's the truth. I trial fitted new repro covers. So I did some research & got stay up float & viton needle, genuine Amal. Upon removal the plastic float was soft as stiff rubber & the tangs were soft & bent.

To make matters worse I had the good looking clear Motion Pro fuel lines which melt really fast. Try to turn off fuel tap in flames. Let me know how that works out... I was still stupid & stubborn enough to use clear after. I'd never do that now. Since God put fire out, I guess he wanted me to keep bike. I believe that!

I filled gap with 1/4" foam tape from Ace Hardware. Of course that is not durable.

I trial fitted new covers. Not much better. So I decided to "fit" the original covers. I whittled the groove wider in the corners & removed the warped thin blade on rear vertical surface of the sealing groove. I heated covers & worked them back to where the fit better. It's important that the retaining nut is not over tightened, which mine never was. At the same time the plastic tube for nut needs a stop. The air cleaner element needs to seal at the same time the housing needs to seal. Flat washers can be used on stud as needed, if needed. The original filter elements I still use & the are not deteriorated. They have tin center with round hole. Later has square hole, but the aftermarket ones that have no tin plate you must be certain the cover tube is supported. Retaining nut too loose & it will come off even with spring washer. So I like to have some support under tube so you can just snug nut the right amount without distorting the flimsy plastic cover.

Now I had decent fitting covers, as good as the repro ones were. I put thin foam tape inside groove in covers. About 3/32" thick, cut skinny to fit in groove. Self adhesive. Was off Mercedes grill edge to stop wind noise. Pretty tough material as far as foam goes. This sealed perfectly but pushed the front outwards. So I made some hooks out of stainless steel. Screwed them to covers. Peened screw in back so nut can't fall off & get sucked in. Some screws are in very think plastic, so I just tapped the plastic & used Loctite 272. Has worked very good for a long time. Saved $100 but more importantly the new would need springs anyway.

I also trial fitted early alloy louvered covers. The shape of the rear is round & leaves a gap, plus the badge looks odd over the louvers. I could fill louvers, but the rear gap is harder to deal with.

On later bikes the filter cover had an over cover retained by springs. I have no real personal experience with those. I really don't know if they help push front of filter cover tight in real life or not.

A lousy photo of lower, but here's the springs. The springs just cured the problem.

I have personally seen 2 bikes with velocity stacks spit back & catch fire.
Don
 

Attachments

·
Registered
Joined
·
209 Posts
Discussion Starter #12
Blimey Don. That's a real horror story. You've made me look at those airboxes and filter covers in a new light! Mine seem to fit OK and there's no sign of any outer cover and it's not shown in the parts book. I'll have to find a TR7RV in a museum somewhere and see what it looks like.
 

·
Registered
Joined
·
2,923 Posts
Hi Andy, Dave, Dave, thanks for posting info on late covers. Andy, look at '78 parts book. You'll see basically has
IMG_0701.JPG
our covers, with the "over cover" that goes over them. The over covers are basically a more streamlined trim cover. They don't actually hold the air filter elements.

Andy, I think your & my side covers are the same.
Don
 

·
Registered
Joined
·
209 Posts
Discussion Starter #16
Hi Dave M - I have the 1973 parts book for my TR7RV and it shows the plastic side covers, just like Don's (I assume Don's is the blue Tiger 750!). What I have is not like the '77 etc one piece side covers. My Tiger looks exactly like yours, apart from my (wrong) front m/g.

The 78 parts book show the outer cover, over the triangular metal side panel and the plastic cover to the air box and filter - which the 73 does not have.

Thonk that's cleared that up - except that Don, you have that spring just above the carb intake, but you don't have the outer covers. What does the spring do?The ali airbox halves are held together at the front side with 2x 2BA bolts, and the plastic airbox covers are held on with a single 5/16 UNF bolt, hidden behind that rubber plug. Or am I still not understanding?

Whatever, what I have survived 1000 miles this summer without falling off so it must be held together well enough!
 

·
Registered
Joined
·
2,923 Posts
Hi Andy, Yes that's my '73 Tiger.
I added the springs. Scroll up to post #11 & it explains why.
Don
 

·
Registered
Joined
·
209 Posts
Discussion Starter #18
Thx Don. That's a very good looking Tiger 750. Hope mine will look half as good, we will find out!

Yes, apologies, missed the part of the post about the spring - fortunately my plastic parts seem to be unwarped and fit well. The bike spent its years in Toronto from new, so I suspect the bike wasn't exposed to the heat you get in Ca.
 
1 - 18 of 18 Posts
Top