Shaving the Piston By Gti (Read 2,550 times)

[Gti]

Does anyone know how to measure and allow the machine shop to know"how" much to shave off to piston in order to use the factory chain when installing a stroker crank (+4).

[justbuggin]

shaving the piston is not gonna do you any good for your chain length you need to retract the tensioner before bolting it to the motor and make sure your chain glides are in there proper place and one of the chains you have will fit

[Gti]

I never installed the chain tensioner at that point of determining that the chain was to long. For the heck of it I did install the tensioner after that to find out if it had any impact on the chain and it did not. Even with the shorter chain I did not install the tensioner. The chain issue is really perplexing me and I am not sure how to even approach this problem. I have a boat load of $ in this project and the chain is holding me up. I could break the chain but am afraid that if it breaks under load.
re
Shaving the piston would allow me to remove the spacer and allow me to install the factory chain. I wish I had the time to work on this now but I am going to be out of country for a month and this is just gonna sit and my mind is going to munch on this project while I am gone.

[sprocket]

What factory chain? Chains come in stock, 90 links, and special use... 92, 94 and 96 links. Shim the jug ..what is the problem?

[Random Hero]

**4mm Extended Stroke Crankshaft.Requires taking Piston to Machine shop or using a Cylinder Spacer.**

Call Walter and see if he can get the spacer or lead you in the right direction.
[phone]

[Gti]

I have spoken to Walter and I already have the spacer from MBE and I have a 94 link chain that when installed the cam kicks up in the rear and forces the cam retainer not to want to sear properly. I just broke one and bought a new one from Scooter Elements. I thought increasing the chain length to a 96 link chain and that one just flops around, so I am at a lost as to what to do. The space is 2.35mm, a 63mm bbk, 61mm head, and a project that I cannot seem to finish!

[Alleyoop]

Well you break the chain and find out how many links to take off and then pin it BUT for it to hold the pin will have to be welded. That is how it was done on bikes without even having to take the motor out.
Alleyoop

[Random Hero]

Sounds like they gave you the wrong spacer. I wish i could remember what space my 63 took..its been along time since i did that install.

[Gti]

I I also bought the smaller 1. something spacer because I thought I Would nee it. Although I did not try to install it because I thought the larger spacer including the gaskets would cover the +4 increased stroke from the crank. I did his because I ruined to heads because of the piston hitting the valves. Honesly thinking about selling this damn engine and getting 232cc kit.

[sprocket]

How much longer is the crank and rod? 4 mm right? So you use a 4 mm spacer and most likely a 94 link cam chain...

[Gti]

I did try that, as well I stacked both of the spacers (2.35mm + 1.57mm) and a gasket and it was still a problem with the 94 link chain being 1 link to short. I would place the chain on the sprocket for the cam and the rear of the cam would not seat right and I broke a can retainer trying to bolt it down, so I ordered the new one from scooter elements and then installed the longer chain and repeated the process with the 96 link chain. The process was repeated and the 96 link chain was about two lengths to long.

[sprocket]

You have the chain tensioner removed from the block? Are certain the cam chain is on the crank teeth correctly? Sometimes they can get off to the side...People put in stroker cranks all the time..I can't seeing it being this kind of problem...the new 63 mm jug is the same length as stock?

[justbuggin]

shaving the top of the piston down is not a good idea as it will make the top of the piston to thin and as soon as it gets up to temp it will blow a hole in it

[Deleted]

Almost everybody here in Puerto Rico takes there pistons to the machine shop to get it shaved and the valve seats done. This will give you more power than just using a spacer! Remember we are the fastest in Gy6 150cc scooters here in the world! What you can do is take the entire engine to the machine shop and they can see how much it comes out of the cylinder and what needs to be shaved and how deep the valve seats need to be done. I have a 3mm Stroker kit in my scooter with no spacer. Took the piston to a machine shop and they shaved it and did the valve seats and its been that way for about 2 years and never ran into any problems. even people here who use the 6mm or the 8.2mm stroker from Taida they come with a huge spacer but still require you to modify the piston.