guys

Guzzi v7c... Nice!

Nope, not for montesa, they use a plastic (pré 2014) or a steel (2014 and on) support, for lights and plate, that bolts on under the original rear mud guard.

The 260 has a bit more torque as you would expect, but to know if it's worth the extra money, you'll have to ride both bikes I'm afraid. The Showa suspension is indeed first class.

What's the advantage of that?

Quite the opposite if you ask me, good for everybody except expert riders. 260 4RT's don't have the light weight and instant power like 300cc two strokes. They're just as fun to ride as a smoker, if you like four strokes, and there's only one way to find that out, go for a test ride. And even then it takes a while to get used to them compared to a GasGas I had, which felt good from the first ride.

Hi John, thanks for the tip, but I already ordered a Mahle piston in France. Good luck with your Metralla build. Guy

And I just got the message that Club Bultaco in France also still have some Mahle pistons in stock. So if anyone is searching for one, contact: http://trial-classic-bultaco.fr/

I was talking about a 84.45 mm piston for the rebuild of my Sherpa 159 Maybe Johnjsy better starts his own topic, because it seems to be getting confusing

Apparently France Trial Classic had a Mahle piston in the size that I need, which is very nice.

Go to link below, cick on "tuning" then "modification's" and then "map switch" http://montesa4rt.nl/

Chest mount And if you are afraid to have an accident, wear a chest protector GoPro with chest mount:

I don't know if it's much more expensive to just buy a 300 RR. It's got a longer stroke, so I guess it'll have even somewhat more torque than just with a bigger bore, like the S3/Mitani kit. just my thoughts

I think it's better to send it in a personal message, just click on his name, and on the right you'l find the "send me a message" button

Quote: "But watch out the piston too has the both holes drilled and the piston pin shaft is too a little bit out of the center." No need to worry about that, it's done for a reason: https://books.google.be/books?id=Yn9F0RhJ0EkC&pg=PA244&lpg=PA244&dq=piston+pin+out+of+centerline&source=bl&ots=SaF7EHQBw4&sig=iSSXHxYKUXyoe5YuebcrJeQpjsg&hl=nl&sa=X&ved=0ahUKEwi8x9-H5NXJAhWBPxQKHR3uAqQQ6AEIHjAA#v=onepage&q=piston%20pin%20out%20of%20centerline&f=false

How much mm or inch is 5% tolerance? I mean, what is the correct axial play between the con-rod and crank shaft? EDIT I just found pschraubers answer: a. Side-play / side clearance limit of the lower con-rod and the thrust washers is 0,25 mm. b. Radial clearance for the bearing is 2,5mm in cross direction at the top of the con-rod! c. If a and b is below the limits but the lower bearing feels rough while rotating the con-rod replace too! Repalce always lower con-rod pin, thrust washers and con-rod together, if you detect one of a, b or c.

When I turn the crank with with the con-rod it runs without roughness or resistance, but I would say it runs very loose, although I can't feel much radial play. The axial clearance between the con rod and crank is 0.6mm, but I don't know how much it should be. I think the pin looks very used (looks like it has been running hot) because the bearing was missing the two spacers, so the bearing could move sideways, resulting in the fact that sometimes only about half of the needle bearing was carrying the load. The inside bearing race of the con-rod (at the small end) has the same discoloration as the piston pin and clear wear marks at the bottom (might also be from the fact that some times only half of the bearing was taking the load. To be on the safe side, I'm going to replace the con-rod.

Hi Scot According to Wossner's 2014 catalog, they only have pistons for the Bultaco TS250, but thanks for the tips

This is how the piston pin bearing was mounted. Some one forgot the two spacers apparently: Maybe that explains the blue heat marks on the pin: Although the piston - cilinder clearance is at the maximum, the rings were still doing their job, hardly any blow-by deposit on the piston.

Thanks Bondy, that's good to know about the In Motion pistons. (although I never really had any doubts about the quality of In Motion's parts ;-)

Thanks, but I fear the shipping costs from Australia might be a bit high. I've also contacted Gilles from France ( http://trial-classic-bultaco.fr/index.html ) but he only has a few Mahles left. Guy

Hi everybody I'm in the process of rebuilding the engine of my Sherpa. I need (among many other parts) a new piston kit. Does anybody have experience with the Italkit pistons from In Motion? Or does some one of you guys know from a secret stash of original Mahle pistons? I need a 84.00mm piston.

I would buy: If it had to be a two stroke: If money is no problem a Vertigo (for the fuel injection), otherwise a Beta 250 or 300 Four stroke: Montesa 300RR (or 260) or the cheaper Beta 4-stroke 300 (or 250)

Ohw yeah!