Model 49 Sherpa T 250 Engine questions

[delxr250]

I am new to Bultaco's and the forum, I have had lots of late 60's and early 70's Japanese bikes in the past and I acquired a #49 Sherpa T 250 that someone had previously taken the motor apart and loosely assembled again.  It was missing the primary chain tensioner, the clutch springs, pins, etc, and a few other nuts.  I am reassembling it now and am running in to issue of the counter weight not going down far enough and how to put the clutch pins in on the springs on the clutch basket.  Everything else seemed to go together good.  We put a new rod and bearing on the crank, new crank bearings and seals, and a transmission bearing.  How does the tensioner mount?  I can't seem to find any documentation on the internet for this model.

Thanks in advance.....Devin

[naichuff]

There should be a screw hole inside the clutch case just below the drive sprocket so the tensioner  trails to the rear(clutch) The basic engine did not vary much I ran an early 5 speed 250 then the early 325 Now a 175 all use the same design

[woody]

When you slide the counterweight on the key can ride up at the back which stops the weight sliding all the way on. Make sure the key is a tight fit, if necessary loctite the key in and let it set, then try again. Make sure the weight is seated properly and the nut torqued up as they can come undone and when it comes loose on the shaft it can sound like the death of your engine...

The clutch springs have cups over the end of them which you can use a pair of pliers on to depress the spring enough to get the pin in. Or you can cut a slot in an piece of the correct diameter tube and use that to compress the spring. Or you used to be able to buy a tool to do the job but not sure who would have one of those now.

Any 5 speed Sherpa manual will have the info you need. Ebay always has them - Haynes, Clymer or you can buy a workshop manual from In Motion (UK) or Hugh's Bultaco (USA) not sure where you are

[feetupfun]

I have an early M49 (4900100) rider and from memory, the primary chain tensioner that it came with is different to later M49 and M80 engines. Maybe just the spring is different. I can't remember if the shape of the arm or the mounting arrangement was different, but it did have a brass rubbing block rather than a rubber wheel.

After working out that the strange damage marks I found inside the primary casing were from a tensioner coming apart, I run it without a primary chain tensioner.

Another thing to watch out for is that if it is an early M49 it might have a clutch that is different to the later single row chain clutches. One of my M49 engines has original fibre plates and the steel plates have no holes. I've not checked if later type (all-steel) plates are interchangeable with that clutch

[delxr250]

Thanks for the input. I have a manual on the way and am going to try and pull the counter weight off again and make sure the key is seated flat.  I'll try the pliers trick on the clutch springs as soon as I know the counter weight is on all the way.  It is a later #49, M4904488.  Here is a couple of pics of my project, before and after so to speak and one of the old boy that I bought it from ice racing it in the unstudded class back in the day.