[Dr. Zo]

Hi,

I am new to the forum. I’ve some experience with motorcycles, first Bultaco Pursangs in the 1970’s, then on to BMW bikes. I had a K75S and rebuilt most of it. Then onto a K1300S, perfect shape and very fast and smooth - passed on to another rider in 2019.

I’m in the northern part of Virgina, in the USA.

Now those have gone and I’ve recently acquired a Triumph T120R. The bike is a 1967 T120R Bonneville frame (DU49062) and the engine from a 1969 T120R (EC 19971). It has been in storage for the past 30 years or so. It was rebuilt in about 1982, with a Routt 800cc big barrel kit. Apparently it wasn’t ridden much after then, the owner being in the military and moving around a bit while the bike was in storage.

So I am trying to decide how to best approach this beast. The Amal monobloc dual carburetors are off the bike, and they have the numbers of “10 66” and “389/95” written on the intake flanges. So I am wondering where to get a rebuild kit for these carburetors - or perhaps new carburetors?

Since the bike was rebuilt in 1982 and not ridden much after, I was thinking of just trying to rebuild the carbs and install them and do a good change of oil and fluids and such and trying to give the bike a go - that is see if I can get it running.

The gas tank is rusted out so I need a new tank. I was looking for something simple, and saw some of the tanks for sale on eBay from India. I’ve heard these are not so great. Although I see they also have an alloy/aluminun tank that looks pretty nice.

I am not trying to restore this bike, but just get it running and ridable - with a look to it being a bit more of a scrambler/desert sled style.

So I am wondering if any of you might know the provenance of the carburetors and/or where to get a rebuild kit for them. Also, any suggestions or a replacement gas tank?

Thanks for any advice. I imagine this forum has a number of threads that will have some great information. I will appreciate any of you having some advice or suggestions about the best places to go for parts and information.

Thank you!

 

[GrandPaulZ]

Howdy!

I replied in the TriumphTalk forum - get yourself a new set of Burlen Amal Premier 932 Concentric carbs and an Emgo gas tank.

Here is your refreshing startup routine - Waking the Sleeping Beast (fluid quantities are slightly different for a twin than for the triples)

Hope you post some pix!

 

[Dr. Zo]

GrandPaulZ,

Thanks for the response and advice - here and and the other forum. I had someone else suggest new carbs and I thank you for the advice on the 932's. I have also heard that Amal 930 Mk1 Premier 30mm carbs are good for this engine. Do you know what the difference between the two carb might be? Also thanks for the "waking the sleeping beast" narrative, which I will need to follow. On the carbs, it seems like the newer model would be a lot less troublesome that rebuilding the old ones?

 

[StuartMac]

Hi,

Firstly, welcome to the Forum.

Burlen Amal Premier 932 Concentric carbs

Amal 930 Mk1 Premier 30mm carbs
Do you know what the difference between the two carb might be?

To clarify:-

. Burlen are the current Amal licencee, their website is linked in your TriumphTalk thread.

. "Premier" are Burlen's upgraded version of the original Concentric. Original Concentrics replaced Monoblocs from part-way through '67. Their primary criterion was they should be cheaper than Monoblocs; they had/have several faults that make them a pita for the way old British bikes are owned and used today, hence the Premier version. (qualified ).

. Apart from that, the only difference is "932" have 32 mm. ID main venturi, "930" have 30 mm. ID main venturi; you might want to measure the ID of the big 'oles in your bike's carb. mountings before deciding between 932's and 930's?

seems like the newer model would be a lot less troublesome that rebuilding the old ones?

Possibly. Your TriumphTalk thread advises you to check the costs. Burlen also make new Monoblocs.

Hth.

Regards,

 

[GrandPaulZ]

Apart from that, the only difference is "932" have 32 mm. ID main venturi, "930" have 30 mm. ID main venturi; you might want to measure the ID of the big 'oles in your bike's carb. mountings before deciding between 932's and 930's?

@Dr. Zo if the intake manifolds measure 30mm, I'd have them bored to 32, and smooth tapering down to match the head's ports.

 

[Dr. Zo]

StuartMac and GrandPaulZ - thanks again for the information. I've posted some more photos on Triumphtalk too. Here are the state of my carburetors.

 

[mach1970]

I am not of the mind set that you should immediately go out and buy new carbs. I have quite a few old Triumphs running monoblocs and they run great. There is nothing wrong with that carb. I would clean the carbs you have and get the bike running, then make a decision as to whether or not you "need" new carbs. Why spend the money for new carbs to find out the engine some serious issues that you don't want to deal with?

As for the India tanks, I have seen both good and bad ones. It seems like it is luck of the draw with them. Look on ebay for a good used tank, there are a lot of tanks on there.

Rob

 

[Dr. Zo]

That is a great idea mach1970. Especially since I was able to get in touch with the previous owner and found he had the bike running last without problems in 1984. The he went off to school and the bike has been in several storage sites since then. The carbs were removed in one move so the moving company could know there was no gas in the engine. I appreciate your comment on the carbs as well as the gas tanks. I've been looking on ebay quite a lot and will continue to do so. Thanks again!

 

[Dr. Zo]

So, I decided that the bike needed a full rebuild. After taking a closer look, and seeing more corrosion, noticing that there were some missing and loose fasteners - and knowing that ultimately I wanted to know the condition of what I will be riding - I removed the engine today. I used Glenn's Triumph book and some other assorted videos to get me through. I was on my own, so ended up wrestling the motor a bit before it came out of the frame. I've got to clean it up a bit on the outside and then will continue the teardown. When I took the exhaust off, there was a lot of rust in there.

 

[Dr. Zo]

I finally removed the cylinders and pistons. The previous owner said this top end was a Routt 800cc kit. It looks like I will have to replace the pistons and I'm trying to determine if the cylinders can be used, that is rebored. I don't know the original specifications of the Routt kit. The pistons have 060 on their domes and I'm not sure how much of a rebore this can take. I'd appreciate any with experience with this kind big bore kit. I measured the top of the barrels as best as I could with my caliper and got, in inches, 3.051 on one side and 3.042 on the other. Thanks for any comments!

 

[GrandPaulZ]

Time for new pistons and a light hone of the barrels.

You'll need to have your machinist check the see if that will be enough; .080 is usually not done, but possible (if you can find a set of pistons!

Those are not 800cc unless you have a madly stroked crank, which I doubt.

 

[Dr. Zo]

Time for new pistons and a light hone of the barrels.

You'll need to have your machinist check the see if that will be enough; .080 is usually not done, but possible (if you can find a set of pistons!

Those are not 800cc unless you have a madly stroked crank, which I doubt.

Thanks GrandPaulZ. With all this I may just find a new top end and go back to the stock size. I will wait till I get the engine apart more to see the condition of the rest of the engine.

 

[StuartMac]

Hi,

may just find a new top end and go back to the stock size.

As you know from your thread in That Other Forum, your Routt barrels more likely started as 750 and have been rebored to +0.060". Aiui, they're basically the same bore as standard Triumph 750 twins? If so, dunno whether there are +0.080" pistons?

Alternatively, if you look for a new top end, don't rule out a new 750 like a Morgo? @rambo Geoff has posted several times that he's run a Morgo for years on his '71 650 without any problems and, having been able to compare the two, he wouldn't want a 650.

Hth.

Regards,

 

[Dr. Zo]

Hi,

As you know from your thread in That Other Forum, your Routt barrels more likely started as 750 and have been rebored to +0.060". Aiui, they're basically the same bore as standard Triumph 750 twins? If so, dunno whether there are +0.080" pistons?

Alternatively, if you look for a new top end, don't rule out a new 750 like a Morgo? @rambo Geoff has posted several times that he's run a Morgo for years on his '71 650 without any problems and, having been able to compare the two, he wouldn't want a 650.

Hth.

Regards,

Stuart, thanks. Yes, as I've been looking online at various kits I am starting to change my mind about sticking to stock. 750 seems the way to go. I've got to get the engine apart a bit more to see what else I might need in terms of major internals, and then I'll hope to put together a good selection of parts. Thanks again.

 

[Dr. Zo]

So I made some progress on my engine tear down on the primary side. I got stopped when I tried to take the rotor off the crankshaft. I don’t have a 2-jaw puller and it did not come off on its own - so I’ll have to get the 2-jaw puller soon to get the primary chain off. I found some parts of very tiny springs in the oily bottom of the primary case. I’m wondering if any of you might know what these could be and what kinds of problems this might indicate with the engine? Thanks.

 

[GrandPaulZ]

Answered on TriumphTalk already:

I can't think of what that spring could have come from, don't thing it's within the original parts specs.

Use a 3-jaw puller on the rotor, SNUG it up tight, then rap the center bolt on the puller to break it free. Too much futzing with puller will loosen the alloy body off the steel hub of the rotor, ruining it. Hopefully, as you're snugging up the puller, it pops free on it's own...

Thanx for cross-posting!

 

[Dr. Zo]

The last few days I made some more progress on my tear down. I’ve got the primary side off as well as the timing and transmission. I was initially stalled by the rotor, but was able to get a 3 jaw puller to get it off.

I noticed a small crack in the primary cover, it doesn’t go all the way through - wondering if this looks of or should I have it fixed?

The crank end on the primary side was hard coming off, it seems the reason might be that the end was a bit bunged up. The primary chain tensioner didn’t appear to have much wear - so perhaps it had been adjusted properly and is still in good shape? The drive sprocket seems to have some wear. Whoever build this before used a lot of goop on top of gaskets!

I had some difficulty getting the advance off as the interior threads would not take my puller. Looking closely it seems they have been damaged, so this should probably be replaced.

 

[GrandPaulZ]

All of those wear parts should be replaced.

Test your alternator rotor for looseness-

View: https://www.youtube.com/watch?v=Nqq_gS_i1yc


Find a good welder and have them weld up that crack, or you can clean it VERY thoroughly, dress it with medium emery paper, clean it again with denatured alcohol, then apply JB Weld clear epoxy and let cure.

The AAU is still re-usable, as long as the springs have good tension and the parts are not sloppy loose.

Sure enough, the spring is gone from the seal.

 

[Dr. Zo]

On to the timing side. Looking at the intake cam gear it looks like somewhere along the line someone beat on it a bit as there are some marks on the face. Also I had a bear getting the exhaust cam gear off because I couldn’t get my puller to engage the threads. I noticed the first couple of threads on the gear were messed up a bit. So I carefully filed the threads a bit with a jewelers file to try to remove the first thread a bit. I finally got the puller to engage by slowly threading it on and off with some oil. Perhaps this gear should be replaced when rebuilding or at least get the threads fixed? I couldn’t get the key out of the exhaust cam.

I seemed to get the gearbox out rather easily. I’m not sure how to evaluate the gears, but they all look pretty stout to me now.

I ended up with one part that I’m not sure where it came from - a thick washer or ? I’ve managed to keep everything else segregated.

Now to split the cases.

 

[GrandPaulZ]

Too late now, but I would have left the cams and pinions in place and checked for runout, then NOT TOUCHED them unless it was excessive, checked against allowable spec.

That is one of two fork rollers that go on the little pins of the fork; they ride in the gearchange camplate slots.