No less than .021 on the Comp. ring (silver one not the black one)(the black ring is not used)

.015 MIN. on the Oil Rails (could be .030 but .015 is MIN)


They send you a 3 ring RING KIT with the pistons... the Black Compression ring is not used... only the Silver ring is used and then the 2 oil rail rings and the Oil Ring....


SCROLL DOWN BEFORE YOU TAKE THIS INFO..... We are having problems with finding the right Gap specs....

Thanks

Tyler
Killer Q...

Nice info Tyler Do you know what the max is on the compression ring?

Where did you get those numbers from Tyler? The comp ring gap sounds huge! The old rule of thumb is .0045" of gap for every 1" of bore size.
(94mm)3.70" = .016" gap
(97mm)3.82" = .017" gap

And that .0045" per 1" of bore is usually on the big end of what people use. Some will use as small as .003" per 1" of bore for single comp ring (no scrapper) setups.

UR RIGHT... MISS PRINT.....

Changing it now....

Just blame your Alzheimer's! Remember!?

After re-reading my post, I appologize if I sounded a little like I was jumping on you. I was just curious if you got those numbers from CP or VCP......or maybe it was from ESP But now I see you are correcting the numbers ASAP. Your service is always PDQ.

Ok, that's enough, I'm going to eat some BBQ.

NO WAIT.... CP... Said that no less than 21 thousands for the Comp Ring... (.021)... and a MINIMUM of 15 thousands for the oil ring..... (.015)...

My Head hurts and the guy is at lunch and we cant get a hold of John....

Also they are 2 ring pistons... he asked me that right off the bat... 2 or 3 ring... i said 2 ... he said no less than .021....

PS... I know you were'nt jumping me....

Wiseco is saying .004 per inch.....

JE is saying .004 per inch....

Engine Builders are saying .0045 per inch....

CP is saying .0055 per inch.....


John is Gonna give me a Call tonight when he gets off work to really get the RIGHT ANSWER.....

Also, when you talk to him, ask him what the piston to cylinder clearance should be for those people who are getting the 97mm. When they send their piston and cylinder out, they can bore and replate to the exact tolerances he specified.

I thought at one time he said around .001" clearance.

Oh Boy... Another Question thats gonna make my HEAD POP..... :lol:


I will do that... I have a list... my #1 question is gonna be... WHERE YOU AT BIATCH.....????? U NEED TO BE ALL OVER THE NET.....

he did get DSL hooked up at his house... I do Know that Much....

I'm pretty sure that's what he wants it to be at. Although I don't have the means to take an accurate measurement, I know my stock bore was/is a honeymoon fit.

What?!?!?! Is your bore snap gauge rented out?

What if the gap is too tight what will happen. The service manuel at least what I could find gave .008 to .014 for the top and .008 to .028 for the oil.

what will happen if the gaps are to tight and did anyone ever get a clear answer for what the gap are to be ????

I did mine per the service manuel. I hope it is right and I dont have to tear this thing down again to file on the rings

i just can't beleive they sell a piston and don't give any specs with it ..... and can't tell you if you call ?????

I have bought MANY pistons from MANY companies. I have never got a ring end gap number. There are too many variables that come in to play. There is a general rule of thumb, but depending on yoru application, your ring end gap can change.

They (VCP) was not at Fault.... CP sent them all the pistons as if they where a Customer and not a Distributor or Dealer.... They boxed them all in one Big Box and made VCP sort them out... then they didnt include NE paper work for VCP and MIXXER (John) is the TECH guy and he is trying to set his new Life up on the NW Coast..... (Hard to get a hold of right now...)

So its not really VCPs fault..... its more CPs seeing as how they cant get it right and havent returned my last 6 calls (maybe it was over kill on the calls but i was trying to find the RIGHT specs for everyone)....

PLUS... it doesnt help that CP was behind on making the Pistons and Everyone and their brother was VERY "HURRY, HURRY" to get the HammerHeadz....

We (not so much me, im just the Speaker of the House) are trying to get the EXACT Numbers that everyone is needing ....

ALL IN ALL .. Its no ones fault.... its just .... Growing Pains.....

then why send them out ... what good is it to me with out any info ??? does anyone have the right infomation yet ?

Becasue everyone and their Brother had paid for them and was Wanting them....

Plus because it is just SOOO PRETTY.....



Still Waiting on the Phone Call from VCP....

oh there a good looking pistion i'll give them that but i just called and talked to vince and they still haven't heard from mixxer

^^^^ HINT ^^^^

i just want to get my bike back together .... so i called , i didn't know when you talked to them last ... i have a question for ya seeings you are keeping track of this thread .... what will happen if the ring gaps are to tight ???

Have No Clue....

Never Had it Happen...

If anyone is currently in the middle of putting one in and needs to know right now, just follow the rules of thumb I stated earlier.

The tighter the gap, the better it will be at containing the compression inside the cylinder on top of the piston where it belongs. The tighter you go the more accelerated the ring wear will tend to be.

My stock bore is gapped at .012", which is just a tad over .003" per inch of bore.

IMO, .021" is waaaaay too big for a single ring piston. I would recommend no more than .016" for stock bore and .017" for the 480.

I would have to agree... My 490 is set at .016....

It was a Big Red Flag when HABIT pointed out to me that the .021 sounded big.... which as i thought about it ... it did sound HUGE.... i had 3 phones i was talking on trying to find info and order stuff for people... Thank god i have 4 lines and a cell phone.... :lol: ... thats why it didnt sink in at first.... But i guess we are still no Farther along then where we where yesterday .....

I do have some New Products comeing in....

Tyler I appreciate you keeping track of this and all the work you are doing for everyone...time is money and you are donating a lot of it...probably the majority of the folks you are helping did not even get their piston from you...

Thanks man...

Thanks.... Im just trying to help PERIOD.... Mike at Luda Called me and asked me and i figured it was gonna be a Big Question so i got on the HORN and started Sweeping the Country for a SOLID ANSWER....

Still Searching....

Mine all went in at .008 tight honda specs, plus the cylinder is like new. It all a game of trail and error. If I go through a set of rings real quick I know it was to tight and I was wrong.

did you have to take anything off the ring to get that clearance ?

BREAKING NEWS-->

After already have this typed up and a long shpeal about this and that and then the Web site CRASHING on me... i am just gonna do it all again....

HERE GOES....


CP pistons Formula is --> .0045 per cylinder INCH + .004.... that is where the .020 and .021 come from.... That was actually a Very highly recommended gap by many builders i talked too...

The 2 ring piston as the HH is (1 compression ring) may be pushed a little closer...

I have talked to 3 engine builders on the phone and 2 here in my local area.... they all said that the .0045 per inch is pretty tight STILL... so the recommend the +.004 at the end as CP does or to go with .005 per inch or .0055 per inch.... .0055 is REALLY BIG.... They said the .005 per inch was the best STRIGHT FORWARD Formula to go with....

so the Formula for these 2 sizes of pistons will be....

94mm (3.70") * .005" = .0185" of gap (<< No less than ) (.020 is recommended)
97mm (3.82") * .005" = .0191" of gap (<< No less than ) (.021 is recommended)

The 2 NO LESS Than numbers where only recommended because of the fact that the pistons in question are 2 ringers....

The .020 and .021 of gap is a Safe bet.... this will have no problems keeping your Cylinder safe from the GOUGING effect of Tight Rings.... and the Bigger the gap the longer the Ring life... To a certain point where it will start to loose compression...


OIL Rail GAPs --> .015 MIN. on the Oil Rails (could be .030 but .015 is MIN)


For the People who are Boreing their cylinder to the 480 or haveing one redone for the stock bores... the Tolerance is .001 and .0015

The pistons where made by CP with a Tolerance of .000001 of an inch.... .. is that possible... ... WOW... Mad Props for PRECISION....

This is all up for debate by people that have thier own numbers but these are the numbers that we found to be SOLID BUILDERS NUMBERS......

i just want to make sure this is where we need to be now that mixxer is back??

many thanks to tyler for covering in my absense!

those numbers are consistant with what CP recommends! i will tell you that i run my ring end gaps tighter (.003" per inch of cylinder bore on my own setups) but i can't officially go against what the manufacturer states because that would be a serious liability issue for me... the manufacturer knows more about the specs than me about their own product for sure!

the most important spec for long life and power is to have the tight cylinder bore tolerance of .001"

honda even specs BELOW .001" in their shop manuals...

Matt Vince and i where on the phone for 1 hr every night trying to figure it out... i had CP on the phone 6 times cause we where WAY over many other Piston Manuf. specs by quite a bit... i was just giving a Safe Number for everyone who wanted their pistons in NOW....

I tried my best and i now look like YOU from Pulling my Hair out.... But it was all in GREAT FUN....

I'm a little confused on this tread. CP says .0055 but then it says CP says no less then .021 and I saw killer put a .18 feeler gauge in his.

Lets make it easy. What size feeler plus or minus for the comp and which size for the oil rings?

Any help would be great cause I'm ready to install today.

The .0055 is multiplied for every inch of bore. Example: Stock bore is 94mm = 3.700776 inches x .0055 = .0203542.

So, a stock bore 94mm (3.70") = .020" of ring gap per CP standards.


Some manufacturer's specs say .045" x bore size = the inches of ring gap.

And just to add to what 29FTEX posted.....

Not only do some manufacturers have different recommended ring gaps, but different builders will also use different gaps. Kind of a personal preference to what they feel is the best. Some people (manufacturers) will tend to lean conservative to obtain the best longevity, while others (high-end builders) will lean more aggressive to get the best performance possible.

So knowing this, this would be a range one could use....

Ring gap per 1" of bore diameter.
.0055" Max (stock bore = .020")
.003" Min (stock bore = .012")

The maximum is a conservative number while the minimum is an aggressive number. You may use these numbers or something in between. I would not go outside of this range, especially the minimum. Tyler using .018" is simply in the middle ground of what is widely used.

Man where do you guys learn all this stuff from? I'm glad I found this site

So If I wanted to go middle ground as well I should use a .18 feeler? And where should I take this reading from? The middle of the cylinder?

The upper to middle is fine.

I'm in no way a motor head, but I did stay at a Holiday Inn Express last night.

Holiday Inn Express

That was funny right there.

not .18 like you said above arrant. it is .018

Thanks ya I meant .018 thanks for catching that though.

Ok, lets see. I am getting the HH 12.25:1 piston. This means that the ring gaps should be as follows:

Compression ring gap: .019" is good

Oil ring gap: .015" is good

And what about the center oiler thingy, umm

Do not use the black compression ring that comes with the 3 ring kit.

I believe you're talking about the oil ring spacer, the squiggly ring.

Gap is .000". You do not want a gap, it compresses when slid into the cylinder.

AAAAAAhahaha, the squiggly ring, ha

I thought so, the ends overlap, I just read someones post wrong I guess and had me scratching my head. So are the gaps i mentioned good?

are these numbers for the oil and compression ring..

Compression ring.

i've rebuilt close to a 50 2stroke engines and i've never checked the ring gap,i use to see the spec. in the box that the piston came in but always thought it came with the correct gapping... .....well out of all the ones i did only two needed rebuilding in less than 6months...

what is the ring gap spec. for the oil ring stock bore....i'm about to change my piston,thats what's got me reading this thread...

anything else i need to look for when i go in theres..

Mixxer e-mailed me that he uses .012" compression ring gap on all his HH installs