Rebuilding a 2 stroke? | Page 8 | GTAMotorcycle.com

Rebuilding a 2 stroke?

Hope it's just the top end - and nothing from the cracked piston or damaged cylinder made it to the bottom end.
You have the cylinder already, hopefully they can get a good size match with a piston and not have to do any more cylinder work.

You should post pics of the piston and damage in the cylinder... maybe some of the more knowledgeable two stroke guys can identify what happened.

Hope you get it sorted.
I asked them to either send me pics or call me so I can come look at it and take pics when they get it opened up.

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Well Pro6 just called me to ask if I have a service manual. That doesn't give me confidence but I guess we'll see how they do.
 
OMG. I just read this. I haven't been logging in here a lot.

Was that the Mitaka Barrel and Piston? Do you have a picture? Do you know if it was the skirt that cracked?

I hang out a lot on the TZ350.net and the Yamaha Past Masters board and there seem to be a lot of complaints that if Mataka's have too much clearance the skirt doesn't last too long, they have an even shorter life than ART or Pro-X. Do you know what the piston to cylinder clearance was when it was built?

Have you thought of Wossner as a replacement with the new cylinder. I've run them in an RZ and I thought they were a really good street piston as the tolerances are pretty close to an OEM cast piston but they are forged. For the RS you would probably be able to run them at around 1.9 or 2 thousands clearance give or take

Its strange that Sandy's not around. Is he running the track days? Not sure where you are located but if it doesn't work out at Pro6 you could try Willy and WASP on Westney Road in Ajax, Vance at Oshawa Precision Cycle on Simcoe Street or Gord Bush at Kipling and Lakeshore
 
I don't know where Sandy is. I don't know how old he is but they made it sound like he retired. I have no idea what the clearance on the Mitaka kit was. Maybe Bitz measured it but I did not. I'm new to this rebuild and 2 stroke stuff.

I've left sourcing the piston up to Pro6. They didn't seem overly pleased with that. They were asking for the service manual to determine which of the 3 OEM piston sizes that are available to order.

Despite telling CVTech I wanted a rebore, piston, and gasket kit both on the phone and in a note left in the box (not mention 3 emails they never replied to beyond receipt confirmation), they only did the rebore and did not supply a piston. After the fact when I told them again I wanted all that they said they would have to order from the US somewhere and it would take some time to find it I told them to forget about it. Of course at the time I didn't think I was going to need it right away.

I told Pro6 I am fine with OEM or Mitaka. I also told them to talk to AF1 Racing in the US if they need help since they seem to be really knowledgeable about this bike. Really I don't care what piston they use as long as it works and lasts awhile.

I also asked them to give me pictures or at least let me know when it's apart so I can come snap some myself.

I'm located near the south end of the Allen. Pro6 wasn't bad for me as I could transit home after getting CAA to tow the bike to Pro6.

Towing the bike to various places is not really something I want to spend money on. I can get CAA to do it but I'd like to try to avoid using up my 4 annual tows on one problem, lol.

I believe I looked up where Gord Bush was located and it was like 5 minutes away from Pro6. Since Pro6 was recommended and they were easier to access transit I picked them. Since they keep asking me about sourcing parts, repair manuals, etc it has me worried but I guess we'll see how it goes.

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That barrel is nikasil?

Pistons for those come in increments of 0.01mm. I guess they need to get one that's matches the CVTech hone or one that's a little oversize and hone to fit.

It would be interesting to see pics if they send some
 
That barrel is nikasil?

Pistons for those come in increments of 0.01mm. I guess they need to get one that's matches the CVTech hone or one that's a little oversize and hone to fit.

It would be interesting to see pics if they send some

I believe it is.

Yes, I figured they'd measure what CVTech did and buy one to match. I'm not sure if they do honing. They made it sound that they also outsource that to places like CVTech but maybe I misunderstood. They agreed with me that CVTech are not good to deal with in their experience.
 
I believe it is.

Yes, I figured they'd measure what CVTech did and buy one to match. I'm not sure if they do honing. They made it sound that they also outsource that to places like CVTech but maybe I misunderstood. They agreed with me that CVTech are not good to deal with in their experience.

CVTech should really have had the piston so they could hone to fit. It will be fine but pro6 will have to have that done. It's just another step

I've been using Mellennium and they make you send the piston or they will supply you with one if you don't
 
CVTech should really have had the piston so they could hone to fit. It will be fine but pro6 will have to have that done. It's just another step

I've been using Mellennium and they make you send the piston or they will supply you with one if you don't
Yes. They told me on the phone that they would supply one and then they didn't and when I asked for one they couldn't even source it.
 
Got a call from Pro6 today.

The piston they got doesn't fit properly. They measured the cylinder and ordered a 53.98 mm piston. The piston that showed up measured 54.something (forget the number they gave me). Apparently the skirt is also tapered so the top will fit into the cylinder but the skirt won't.

So they called me to make me choose out of a few options:

1. Order another Vertex piston. It might show up exactly the same.

2. Order an OEM Aprilia piston from the dealer.

3. Send the cylinder I just got from CVTech back to CVTech along with the piston we got and have them bore the cylinder to fit.

I guess another option would be to find another place that can rebore/replate the cylinder.

I'm kind of stumped as to which is the best option. I'm open to suggestions.
 
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Got a call from Pro6 today.

The piston they got doesn't fit properly. They measured the cylinder and ordered a 53.98 mm piston. The piston that showed up measured 54.something (forget the number they gave me). Apparently the skirt is also tapered so the top will fit into the cylinder but the skirt won't.

So they called me to make me choose out of a few options:

1. Order another Vertex piston. It might show up exactly the same.

2. Order an OEM Aprilia piston from the dealer.

3. Send the cylinder I just got from CVTech back to CVTech along with the piston we got and have them bore the cylinder to fit.

I guess another option would be to find another place that can rebore/replate the cylinder.

I'm kind of stumped as to which is the best option. I'm open to suggestions.

The piston will be wider in the skirt than at the top to account for the heat and expansion differential.

From what I can recall those Pistons come in 5 sizes from 53.96 to 54.0. It sounds like your cylinder plating was honed for the 53.98 piston - right in the middle. You could have them order the "C" size piston or send the barrel and piston to CVTech to hone to fit. They should really have done it in conjunction with the piston anyway.

The advantage to getting the 53.98 piston is that you can replace them with the D and E oversized as the cylinder wears with just a quick hone

I should have a vertex catalog somewhere. Let me see if I can find it and find the part number.
 
53.98 is what they ordered. It's even stamped on the piston they said. But they measured it at 54.004.

Pro6 told me you are not able to get Vertex pistons for this bike in Canada. Not sure why they didn't pick something else.
 
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You are right. I found the 2015 catalog and that is the only size that is listed for the RS 125 although they have different increments for most other bikes.

That sounds like a manufacturing or packaging issue. Could they order Wossner or Mataka or even OEM?

I ordered Wossner dictly from them and got a set of RZ pistons shipped from the US in 4 days
 
You are right. I found the 2015 catalog and that is the only size that is listed for the RS 125 although they have different increments for most other bikes.

That sounds like a manufacturing or packaging issue. Could they order Wossner or Mataka or even OEM?

I ordered Wossner dictly from them and got a set of RZ pistons shipped from the US in 4 days
Yeah I'm trying to take it up with AF1 which is who they ordered the piston from. First thought was wrong piston in right box but no, the part numbers match and are correct. So I'd agree that it seems like a manufacturing error but I haven't heard back from AF1 since I got the part numbers from Pro6.

Not sure why they're putting me in the middle. If it's sized differently from what they ordered they should be able to get a replacement free of charge.

I don't know what's going to happen but I know it's going to cost me a lot.

AF1 lists Mitaka, OEM (Aprilia), Vertex, and lists rings for a Pro-X piston so I'd presume they can get that, too.

Maybe they picked the Vertex because it has a molybendum coating which the others don't list?
 
Argggg.....

May have spoken too soon. Wossner sizing starts at 54.005.

could you give winners circle a call tomorrow. They are in markham. They carry pro-x and see if they have or can get a piston. 905 475 2552.

But I agree. Pro6 should be sending it back if they ordered it. And I don't think that that piston should cost either you or pro6 a cent as its not right
 
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Will do. Thanks.

I'm eager to try those larger pistons sometime. So far the bike has been through 3 pistons (2 from me, 1 from the first owner) but they take the cylinder with them every time.
 
Oh I just noticed you asked some stuff about the piston. I haven't seen the damaged one yet so I can't say if the skirt is cracked. I did not measure the clearance when it was rebuilt. Bitzz rebuilt it before but even if he measured it I doubt he remembers what it was. Before he rebuilt it, it had a Mitaka cylinder and I presume piston as well and the piston skirt looked great. Still had the hash marks on it that are supposed to wear off over time.

I see Pro-X pistons go all the way down to 53.95 so that should be a valid option. I'll call Winners Circle later today.
 
Winners Circle can get a Pro-X piston but it'll take 1-2 weeks as it would come from the Netherlands.
 
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Well AF1 sent Pro6 return info but Pro6 is worried the refund will be denied because the return info said something about any scratches in the piston being grounds for refusing the refund and they say it came with scratches.

They're suggesting I send this piston and barrel back to CVTech to fix.

What a mess. Guess I'll be trying to argue with CVTech. Anyone speak French want to argue with them for me? Lol

Maybe I'll ask my gf but she knows nothing about motorcycles so might not have the correct French vocabulary.
 
It seems like AF1's problem. They sent something that was not as ordered and not fit for purpose. It's pretty bad customer service if they won't exchange it. They should be responsible but PRO6 should be arguing that with them.

If it were me I'd just get the right size proX and drop it in. It also leaves room for a hone and a .01 bump if you do get any wear.
 
Ok so here's some updates on this frustrating process.

AF1 originally told me if the piston size does not match what was ordered they can do a postage paid return.
Then they told Pro6 that since we're in Canada they cannot do a postage paid return but they will do a return where we pay for shipping. They also included some fine print about how if there is evidence that the piston has ever been installed, such as small scratches, they cannot accept the return. Pro6 said it arrived with the box open and evidence that it had been installed already so they were concerned the return would be denied anyway.

Then AF1 told me they cannot guarantee exact piston size and none of the pistons they have access to will be close enough to fit. They said they want to help me but I went about it all wrong and I should have had the cylinder honed to match the piston in the first place. They also said in their experience you need to rehone the cylinder every time you do a rebuild on this bike, which is news to me but again, this is my first 2 stroke. I thought it was normally just a piston, rings, and gasket unless something goes boom like always happens to me.

I contacted Vertex USA and they told me that is wrong. The piston should be pretty exact. They then told me to contact Vertex Italy because that is the only place that could have sent this piston to AF1 or Pro6 as it is not normally available in North America at all. At this point I never ended up contacted Vertex Italy as I had given up on getting the piston replaced at this stage.

Then I contacted CVTech and they said it should fit and if there is a problem they will fix it. They asked for some numbers from the cylinder which would apparently indicate the coating thickness. Since Pro6 has the cylinder I asked Pro6 to contact CVTech to give them the numbers they need.

This morning Pro6 sent me an email asking if they can send it back to CVTech for reboring. Assuming this would be as costly as the original repair ($400+) I asked them if it would be free and they said CVTech didn't say anything about that. So I called CVTech and they told me that yesterday Pro6 called them and the mechanic was able to make the piston fit by putting it into the cylinder from the bottom. They were trying to put it in from the top but since the cylinder bore and piston are both tapered it can only go in from the bottom. CVTech said this is very common for high performance engines. The rep said when he talked to them yesterday everything was good so he was confused as to why they would waste time and money sending it back to them if it fits now but he will rebore it for free if it doesn't fit. Apparently this normally only costs $30 anyway so I was worried about hundreds of dollars for no reason.

So I called Pro6 back and they said they have never seen an engine with a tapered bore and that yes, they did get it to fit yesterday (this is the first I had heard this) but they were concerned that the clearance is too tight. Apparently the clearance is minimum 0.0005 inches and maximum 0.0011 inches which they think will cause it to seize if they put it back together like this.

I did some research and apparently nominal clearance is 0.02 - 0.035 mm which is 0.00078 - 0.0014 inches so it does sound a touch tight.

I told them CVTech thought it was fine so to call them back again before sending it to them because if CVTech gets the parts and says it's all fine they'll just send it back to Pro6 and I'll be out like $60+ in shipping the damn thing back and forth and almost 2 more weeks of not riding.

Overall, not too pleased with any of the players in this game but it looks like things might work out soon.
 
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