1976 Suzuki TM75 O/S piston

[smackdaddy]

My 1976 Suzuki TM 75 has a bore of 49.014MM. Can I bore it out to except a 49.5MM Piston? Also does anyone know what the stroke is for this piston?

[Rambler]

you will REALLY need to check on the construction technique employed on that barrel
as the cyclinder could well be just a micron of coating applied with high voltage
and as such cannot be bored at all
76 is a while back, but it was happening then

full tech specs for the machine will be in the manual
Haynes may well do one for this

for details like that it's best to have it in writing
as memories can fade

is there a need to swap pistons
or are you just wanting to do it ?

[Welsh Wizard]

Welcome,

As Rambler states many Jap bore are coated and though, ,36 mm is less than .o15" it could be way over the depth of the coating, also you just can't use any piston as the rist pin on the piston has to have the correct bore and be the correct distance to the head of the piston, as if it is not you could end up with the piston either smashing into the cylider head or being so far away from the top of the bore that the compression has been lowered that much the engine would be totally flat.

Have a word with a dealer that handles rebores regularly, he may well know the answer.

[smackdaddy]

The cylinder, rings and piston were badly scored. It was bored oversize before I had it honed. I have talked to Wiseco and maybe some Yamaha piston will work. You're right, it has to have the same dimensions to work including the pin placement in the ring grooves. I am going to try LA Sleeve but I don't hold much hope for that either. I can't seem to find a replacement stock cylinder either or else I would start with a stock piston which I can find on e bay. I might have a white elephant on my hands. I don't know where to go with this now. Maybe part it out. Any suggestions would be greatly appreciated. I have a 13 year old that is dying to ride the bike.

Thanks for your help

[Rambler]

have you tried to see if there is a different engine that will fit ?

as in that model must have been superceded, could you try and determine the history / development of said model ?
and see if a later model engine will fit ...........
at the very least make the aforemetioned 13 year old work for his ride

[smackdaddy]

I talked to a mechanic and he said that the piston has the Suzuki logo stamped inside and should be the stock size . I don't know if Suzuki made O/S pistons for these TM 75's. If it is the stock size I'm in tall cotton as there are quite a few available on eBay. I might get the .25 over piston kit as this would allow me to remove all of the bore scratches. As far as the boy doing any work on this bike, forget it. He's not at that stage yet. I figure that when it breaks down the next time, I will make him assist in working on it. I have been showing him the steps that I have taken to remove upper end but he just seems interested in riding the bike. Some kids just don't have the mechanical inclination.

Does anybody know how to adjust the starter plunger on the VM 16SC? I am not familiar with them and I can't find out by research of any sorts.

Thanks to all of you who responded. I'm sure I will need help in the future.

[Rambler]

luck to you then
hopefully it will all go well ............

as for #1 son
maybe he might listen if you say clean it BEFORE you get to ride it
as well as after natch

[smackdaddy]

I purchased a .40 over upper end kit and had the cylinder re-bored. The bike is still weak at low to mid range throttle. I had the exhaust system cleaned out and found the spark arrestor was plugged up. Put everything back together and it starts and idles fine but still has a weak low to mid range power. Pulled the carb and checked the specs and that was okay. It feels like it's loading up at full throttle. I don't know where to go from here. Could it be I need to re-jet the carb because of the increase in CC's? The throttle needle is set at the 3rd. position like the manual states. Any help would be appreciated.

[Rambler]

re-jetting is a good idea, but it can get fiddly
I would make sure the bike has been fully serviced recently too
or at least get a new air filter installed

I had issues with a Z1000 years back with a new exhaust came a weak mix with NO pull at all
re-jet did it, but it took feckin ages to get it tweaked just right

luck to you