TT & TT600R conrod

[Tommy10bikes]

I did a resto on my TT600 ( 59X ) a few years ago and over time it has started to have a slight knocking noise on the top end,
also i has a TT600R that has started sounding the same. My initial thought is that its where on the little end on both bikes.
My question is, does anybody now a good supply of con rods for the TT models and are both con rods the same for the early TT600
and the TT600R or fro that instance any other XT600 model.

Much appreciated in advance

TTB

[ActionManMelb]

Hi Tommy,

Con rods for our bike are starting to be a problem as all the NOS stuff dries up.

There are three or four different varieties of con-rod for the 600 models as Yamaha tried to improve durability within the constraints of the original crankcase and crankshaft design.

First design from 1983 to 1989 (kick) used a 34 x 42 x 20 con-rod with side washers.
Second design for electric start models from 1985-89 was 35 x 43 x 20 with side washers.
Third design all models90 onwards used 35 x 43 x 22 rod with no side washers.

There is a company in Japan making the 3rd design.
http://www.tkrj.co.jp/product/m-connecting-rod-kit.html

I was thinking of contacting them to see if they would make low volume runs of the earlier designs. But would imagine the minimum order would be at least 100 units (times $100 =$10,000!!)

I have also found a Suzuki BE bearing that is 34 x 43. This would allow the fitting of a late rod with an early crank. This may offer a partial (stronger?) solution.

[Tommy10bikes]

Thanks for highlighting this AMM , i did find the webpage you linked but i didnt know there where 3 different designs.
I can get NOS still i think but damn expensive as its not the big end thats gone but the little end.
I did speak to an old speedway rider once who told me to ream out and press in an oilite bronze bush then ream out the
ID of the bush, any of you guy had a go or now how easy it is.

If not then it may be me who is going to be the guinea pig.

Cheers TTB

[ActionManMelb]

The small end is copper plated at the factory to act as a thin copper bearing.

It should be possible to reclaim a rod by re-plating the small end and reaming back to STD size.

I think BSA singles from the 50's used a thin copper bush (1.0mm thick) in the small end.
I will try to find out more about their method and see if it would work on the Yam's.

[marcm]

small end in rod seems quite a common ailment and i think is quite likely cause of a lot of peoples clank clank noises from motor..
mine sounded poorly when i first got it back in july,unfortunatly its not the nicest of of things to have to face,the fact that you need to strip motor and buy a rod.
i was very lucky to find a new early rod and big end on ebay for 17 quid or so...some small consolation to just spending 300 quid almost on gearbox parts..

[Tommy10bikes]

It does seem to be simple idea and plausible , i have found a supplier of oilite bushes in metric sizes but now you have me thinking about copper plating , after all there cant be too much play. I have a spare TT motor with a knackered bottom end so i will see if its an easy enough job to ream out the end whilst the bottom end is still together.

TTB

[xtzrick]

The small end is copper plated at the factory to act as a thin copper bearing.

It should be possible to reclaim a rod by re-plating the small end and reaming back to STD size.

I think BSA singles from the 50's used a thin copper bush (1.0mm thick) in the small end.
I will try to find out more about their method and see if it would work on the Yam's.

I was going to suggest Vander had his small end metal sprayed to build up the damage, reamed then coated with a bearing surface, for the engine he's building, but was unsure about accuracy. (Memories of mates having bearings fitted to their "chocolate cam" Hondas, which siezed after a bit of use).

Having said that a con rod should be easier to aline than a head.

In the '90s I read an article about some Yam small ends being a bit thin & one tuner always had the small end metal sprayed to build up strength.
Just something to think about before you fit a bearing.



Rick

[74xt60074]

i have just rebushed a 600z con rod it is at present 22mm bush/22mm pin but i am unable to get a clearance figure to ream to.... any one have any idea of the pin clearance size?

[ActionManMelb]

22.01 mm or about 0.0004" clearance.
Just enough for a film of oil.

[Doubleyoupee]

22.01 mm or about 0.0004" clearance.
Just enough for a film of oil.

How exactly is the small-end oiled?