| Author |
Message |
malcolm harrison
| | Posted on Tuesday, May 27, 2003 - 9:11 am: | |
what is the general thoughts on the best pistons for racing, have used wiseco in the past but are very exspensive try to keep them for the manx malcolm |
Adrian
| | Posted on Tuesday, May 27, 2003 - 12:31 pm: | |
Nearly all of us use the single ring Honda CR125 pistons. I'm not sure if they are much cheaper though!
Another popular choice is the twin ringed Suzuki RGV250 MKIII pistons. |
Adrian
| | Posted on Wednesday, May 28, 2003 - 5:45 pm: | |
I just had to buy a new pair of pistons - £56.00 each for a complete piston! They are patterns, but good ones. They come in 0.25mm oversizes too which helps. |
Dr.Hill
| | Posted on Saturday, May 31, 2003 - 1:11 am: | |
Hello Adrian,
What year are you talking about for the CR125 and RGV250 pistons? Do you have any parts numbers? I recently bought a set for my '66 T20 from vintageparts.net that were .5 over. However, when I went to put them on the other day, it seems that there is more clearance inside of the piston around where the rod meets? It seems to have too much play side to side and I'm worrying that this set is not going to work. Even worse, I've already had the cylinders bored and matched to the set. Thanks! |
Adrian
| | Posted on Saturday, May 31, 2003 - 7:56 am: | |
Hmm...bad reboring by companies is commonplace unfortunately. What kind of clearance size are you talking about though?
Pistons are slightly tapered and are widest at the skirt. A clearance of about 3 thou (at the skirt) is what you want, although you can run them much bigger than this - my racer was running 6+ thou until this weekend (I've just rebuilt it) - and that was with single ring pistons!
If it is for road use, bang it all together and use it - it will be fine.
I wouldn't recommend CR pistons for road use as they are single ringed, but the RGV ones are good. I don't have a part number though, but if you ask for MK111 ones, you can't go far wrong.
Incidentally, CR pistons come in 0.25mm oversizes, which is handy.
|
Stuart Holdaway
| | Posted on Wednesday, June 11, 2003 - 1:35 pm: | |
Dr. Hill I take it you are talking about the clearence between the small end of the rod and the inside bosses of the gudgeon pin hole.
There is usually a good amount of clearence here as the rods side ways movement is controlled by the thrust washers at the crank end of th rod on these motors.
Some motors like Husqvarna's had the rods controlled from the piston end by having spacers between piston and rod.
Unless there is not enough material in the piston bosses for good strength you should be ok |
John Leech
| | Posted on Saturday, June 03, 2006 - 2:58 pm: | |
Wiseco pistons supplied by Vic Eastwood! Better than Prox and machined from solid billet, Not cast like the Prox alternatives! CR125 1987 model! |
Adrian
| | Posted on Sunday, June 04, 2006 - 11:17 am: | |
Hi John
Danny Pullen told me that he used Wiseco pistons in his T20 and the ring land below the ring kept breaking away by the piston cut-out. He said that the amount of ringland on the CR piston just wasn't enough for his T20.
I was going to try Wisecos, but the trouble that Danny had put me off.
I do agree though that Wiseco pistons are superb normally. They have transformed the Spencer Suzuki T200 - it had a lot of piston and ring problem but the use of Wiseco pistons has totally stopped this. |
John Leech
| | Posted on Tuesday, June 06, 2006 - 2:27 pm: | |
Adrian, i have not had any problem with them, i think, be it my opinion that they are the better piston! Ps know anyone wanting to buy my bike? |
Adrian
| | Posted on Tuesday, June 06, 2006 - 6:51 pm: | |
I agree that they are a better piston, but Danny's experience put me off.
Regarding the bike, sorry no. The 250cc twins class is slowly 'dying the death' at the CRMC. No one seems interested in 250 twins anymore unless they are competing in the Manx. Sad isn't it?
All the best
Adrian |
Ellis Moore
| | Posted on Monday, June 12, 2006 - 10:55 am: | |
Hi everybody,I have used a pair of Wiseco 1987 CR125 pistons in my Kawasaki A1 racer with no problems,redlined at 11500rpm.I ran these pistons for approx 1500 race miles,changed the rings twice during that time and it finally failed when the ring peg on one piston wore away and let the ring end into the exhaust port.It still did not collapse the ring land though.I would have no hesitation recommending Wiseco's providing that they are set up correctly regarding squish clearance,bore clearance etc.
Regards, Ellis. |
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Advice, help, chat, whatever!