Yamaha 130 V4 Project Build.

**Dave Strong** · 04-08-2015, 10:30 PM

So in inches your .015- .017" ?

Dave

**FMP** · 04-08-2015, 10:40 PM

I think the yami paper says piston .003-.005in total? But you're using piston brand ? Can't make out the end gap. Wouldn't think it would be more than .004-.005in X bore for gap ?

**Mr. Demeanor** · 04-08-2015, 10:40 PM

Yes .012 - .016 or .30-.40mm.

And yes, I just ruined 3 sets of rings. I was sitting at the bench at looked down at the manual and well....in my mind I saw 30-40 thousands......

I was thinking about it later and thinking damn that seems big LOL. Anyway, the good news is I have 4 sets of brand new pro marine rings on a brand new set of 20 over pro pistons I have. I can use those but I am going to call Pro and see if they have the Vertex rings. I am tied up tomorrow and Friday anyway so I can get them and assemble this weekend.

If anyone building a V4 is interested I have 4 brand new Pro Pistons that have been finger ported and 4 brand new big wrist pin OEM Yamaha connecting rods. The pistons could be used in a non-finger port motor. The holes are there they just wouldnt do anything.

Hey....at least I admit when I F-UP and I caught it before it went together

**FMP** · 04-08-2015, 10:47 PM

DAMM, better now then later , bright side.

**Mr. Demeanor** · 04-08-2015, 10:57 PM

Yup...I dont know wtf I was thinking LOL.
When I put the first ring in and squared up there was no visible gap at all and it all went downhill from there. It is tight.

**Dave Strong** · 04-08-2015, 11:18 PM

Damb Jap's listing specs in metric.lol

Dave

**baja200merk** · 04-09-2015, 09:00 AM

.008 is loose for cast pistons. Won't hurt anything just have a little rattle till it's warm

**Mr. Demeanor** · 04-09-2015, 10:47 AM

Yup a little loose but not worth 4 new pistons and finger porting all them.
Pro doesnt even have Vertex rings in stock. I asked how long to get them and they said they would have to order thousands (basically they arent going to do it). The Pro rings are the same dimensions.

**FMP** · 04-09-2015, 10:56 AM

Good, so you fit the ring for the piston that is clearanced .008 and the end gap was so tight you couldn't measure it? Sorry I'm fighting a head cold today and I'm a little slow on the uptake ,but how do you get near zero end gap for a ring that the piston has .008 clearance, or did you next size up the rings? In this case it's 20up I think. Or is file to fit from zero gap the norm. for Yami replacement rings?

**Mr. Demeanor** · 04-09-2015, 11:29 PM

Ill let you know after I start over tomorrow. I obviously had my head up my ass the other day so Im not counting anything out.

**mrcrsr** · 04-10-2015, 06:26 AM

chris, what is the bore size, in sae! i would set the ring end gap up on the loose side, there is a saying, if you make the ring end gaps too tite everyone will know, if you make them loose only you will know! that sounds weird to me about the rings being that tight though, especially with .008 p/w clearance.

**Mr. Demeanor** · 04-10-2015, 07:56 AM

Ill look at it later today. Got problems with the furry cat this morning and have to take her to the vet.

**Mr. Demeanor** · 04-10-2015, 03:07 PM

Ok so this is kind of interesting. The Pro Marine rings fit .005 tighter (less end gap) than the Vertex rings in the same hole.
The Pro rings put me right at .019 end gap which is what Vertex calls for a little more than what Yamaha calls for.
The Vertex rings in the same hole have .024 end gap.

The rings are identical in height and width.

So if your a little loose a set of pro rings might get your end gap down.

Lets just forget about everything else I said about rings LOL

**FMP** · 04-10-2015, 03:20 PM

That's right out of the bag, without file to fit: Pro .019 and Vertex .024? Same profile cross section shape . So how did you get the 0 gap tight, wrong size ? Now you can .019 top and a hair more lower. While your at it check the bore at 4 places.

**Mr. Demeanor** · 04-10-2015, 03:39 PM

Originally Posted by FMP

That's right out of the bag, without file to fit: Pro .019 and Vertex .024? Same profile cross section shape . So how did you get the 0 gap tight, wrong size ? Now you can .019 top and a hair more lower. While your at it check the bore at 4 places.

Like I said, ignore my previous statements about zero....
I never actually measured it, just looked in and couldn't see a gap but I am blind in one eye! Maybe thats the eye I was looking with.
I did ceck one down pretty far and it was the same. Machine shop said they were straight when they honed it. The really only gave it the lightest hone to get me some cross hatch for the new rings. Next time it comes apart Ill have to go up a size or maybe try forged pistons but lets not have that debate now!

But yes, right out of the box/bag brand new rings Vertex vs. Pro the Pro are .005 tighter which actually works well for me.

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