PDA

View Full Version : Stroker pistons



Sport Scout
07-02-2009, 11:49 PM
I have standard bore resleeved sport scout square base cylinders. The engine is stroked with Indian parts. Any source for standard stroker pistons? Or how far can I bore out the sleeves to accept seemingly available oversize stroker pistons?

inrustwetrust
07-03-2009, 06:35 PM
Cushman pistons were the pistons commonly used years ago. 1972 honda XL250 pistons are the latest and greatest. The Honda standard pistons are about .040 OS and you need to re-bush the rods to a slight undersize and open the pistons up a little to accept the Scout rods. If you were re-sleeving it is best to let the sleeve fit close to the flywheels to keep the piston in the hole, as they hang out a lot otherwise because of the stroke job. I looked at the Cushman pistons as an option and did not feel that they could hold a candle to the quality of the Honda or Rocky's aftermarket pistons.
You will like the power-plant when you are done.
You should consider balancing the flywheels before final assembly. I have found 55% balance weight to be good for the stroke job.

Sport Scout
07-26-2009, 06:32 PM
Thanks for the tip on Honda XL250 pistons. In your opinion, will boring the sleeves to fit the Honda pistons weaken the sleeves?

Also, I have to make a valve quide which will be +0.005" on its outer diameter to compensate for a damaged valve guide hole in the cylinder. Would you make the guide from aluminum bronze or use the original material which seems to be cast iron?

Thanks for your input.

indianut
07-26-2009, 08:05 PM
I would get a stock heat treated guide then press a cast iron sleeve onto it then grind or turn down the sleeve to an oversize After re-boring the guide hole perfectly round again. That is if oversized guides are not available.

T. Cotten
07-27-2009, 05:19 PM
I have found 55% balance weight to be good for the stroke job.

IRWT!

What was the standard stroke's factor from the Wigwam?

Thanks in advance,

...Cotten

Sport Scout
07-29-2009, 11:56 PM
Thanks for the excellent info. Also, when you recommended XL250 pistons I started to look up the pistons. I was worried about the 0.040" bore difference. Turns out Honda XR250 pistons were 73MM for a number of years. That translates into 2.875 (STD Scout Bore.) The piston's pin diameter is 19MM which is 0.748" American. Gonna buy one to see if it will fit. Once again thanks for the info. Dean

Sport Scout
09-15-2009, 11:21 PM
The Wiseco piston (P/N 4466M07300) will fit Scout standard bore with a bit of honing. However I had to machine the pin boss to clear the scout's rod end. I was mistaken about the pin diameter, ihe Honda pin is 17MM. Will have to machine a rod bushing to accept the smaller pin. Currently machining a sleeved valve quide for my cylinder's damaged guide boss. Will let you know of results. Thanks

Sport Scout
10-12-2009, 11:39 PM
Used drill rod to make a sleeve for standard scout valve guide. Undersized guide slightly and heat shrunk drill rod sleeve. Installed modified guide with 0.002" T clearance and cut seat. Perfect!

mdunn
10-22-2009, 12:34 AM
I have standard bore resleeved sport scout square base cylinders. The engine is stroked with Indian parts. Any source for standard stroker pistons? Or how far can I bore out the sleeves to accept seemingly available oversize stroker pistons?

I have a source for standard Stroker pistons but its too late now :(

Sport Scout
12-21-2009, 11:26 PM
I tried to E-mail you but maybe it did not get through. Still not too late! I prefer the original stroker pistons. IPE in Europe came close but no banana. Need pistons compatable with a 45 in scout modified to use chief flywheels, resulting in 57 cu inches. Can give you dimensions such as compression height if you are interested. Thanks Dean

indianut
12-27-2009, 07:29 AM
Contact Venolia Pistons. They will make you 2 pistons to your specs at a Very Reasonable price!

Sport Scout
02-26-2010, 09:25 PM
Venolia Pistons located in California made exact duplicates of my original stroker piston. Also supplied pins and rings. Pistons, rings and pins were right at $400.00 (Tw0 Cylinders). Once again thanks to AMCA member for guidance.

Tom Lovejoy
02-27-2010, 12:31 AM
I have Venolia pistons in my Deluxe, 5,000 miles so far, very pleased with them. Their good folks.