Top end rebuild on a budget.

[meanEG]

I am sorry if I was coming off as a douche bag. I was never trying to challenge anyone. I realize that I am new member here and I am here to learn as much as the next guy. I was tryin to throw my .02 in to help out a fellow rider. I looked into the forged piston stuff after you mentioned the PTW and it appears that, like you said, over the years the PTW have tightened up. I guess the guys that taught me years ago, were taught years ago as well and I was misinformed. I noticed that the stock PTW from the OP was stating .0022 was max. That is also what I was basing my statement on, remembering PTW on forged pistons were .003-.005. Please Gary, at no time was I trying to challenge you at anytime. If I did, I apologize.

After re reading my above posts, I definitely looked like an idiot. I plan on sticking around for a while and please let me back in the circle... Again, I was not trying to be confrontational. I seem to have issues with that. I always enjoy reading your information on carbs as well grizld1.

 

[hooser]

I do not take things personal here, just try to put what I learn or know. I stay of off lots of posts because there are people on here that know better, especially with the stock carbs and electrical, just don't use them. If you want aftermarket carbs or ignitions that work then see me.
I don't think you look like a idiot just maybe not up to date on the Pistons and with cars I do not know what is out there so you are ahead of me there. We all need each other. Gary

 

[grizld1]

Gary, I commend your modesty, but I won't delete anything. You learned the right stuff from the right people, and more than that you paid your dues to learn it and you now make it available to others. You deserve respect even if you're too diplomatic to demand it. Flag, apology accepted; but let's be clear about something. Your intentions may have been good, but you stated spurious information as fact and continued to blather about your "experience" when corrected by someone who knows not only from theory and published specs but also on a hands-on basis. That sort of behavior isn't helpful to anyone, least of all to yourself. This forum would be much improved if members would offer information on what they have done, not what have only read, heard, or guessed.

Webbie, I think where things were headed before this diversion is that if you install 4th over (76 mm.) pistons you'll have 2 standard oversizes and 2 big bore steps to go before you even need to consider new liners (or used but unmolested cylinders, which would be much more economical). You're doing the right stuff and asking the right questions--good luck!

 

[retiredgentleman]

Quote; " This forum would be much improved if members would offer information on what they have done, not what have only read, heard, or guessed."
That is the best advice I've seen on this site for a long time. There are so many "internet myths" floating around on these sites!

Some of my favourite internet myths:
"I've heard that the stock OEM alternators are (weird, crap, poorly made etc.), so I guess I will buy a PMA to upgrade my bike"

"When I rev up my engine, I can see my headlight get brighter, so I guess my charging system is working great"

 

[webbie]

Webbie, I think where things were headed before this diversion is that if you install 4th over (76 mm.) pistons you'll have 2 standard oversizes and 2 big bore steps to go before you even need to consider new liners (or used but unmolested cylinders, which would be much more economical). You're doing the right stuff and asking the right questions--good luck!

I had no idea there were standard oversizes beyond 4. But regardless, yeah that's my thinking. If I understand correctly, you can safely take 3mm out of the stock liners, so there's room to grow.

Thanks!

 

[hooser]

My JE are 3.051/ 77.4954..For some this is not the best way to go, once there you have no where to go unless you re-sleeve back to stock or go to the 80mm (3.151) . Gray

 

[Jack]

I was speaking g from automotive experience only, but theory was applied regardless of manufacture. .0025 is pretty tight for a forged piston IMHO. Usually .004 in smallest I have ever seen. Also your rebuilder might charger a fee to rebore a second pass.

If your gonna run it hard,then .0025 would be to tight,I know of a few people running JEs on the loose side of .006 for insurance and i have a set of Arias pistons that'll be set up loose.006 because of how their ground,etc

 

[650Skull]

webbie, as a general rule. From a standard, 75mm bore, the general term is, the oversize pistons/bore goes up in increments of .25mm, or 1/4 of a mm, up to 4th oversize, roughly 670cc or 1mm. This was the Yamaha standard for the XS650. Aftermarket manufacturers offer a 700cc, (2.5mm), and the 700cc can be bored into the standard liners, but they, (liners), become very thin. Been pointed out, the machining for the 700cc has to be done very carefully and in smaller increments due to warping if to much meat is taken off in a run.

NOTE; These figures general and not a precise measurement in a mathematical mechanical sense

Look for a second hand set of barrels that have some damage or have been taken out to 4th over already. gggGary or DaddyG may be able to help of post in the classifieds.

 

[650Skull]

Okey now who do we believe. I have never raced an engine, only ridden and done general work on my own bike. So from a laymen point of view, who has respect for Grizld1 and Jack and know Gary has experience in racing and selling XS650 products.

A newbie made a statement on forged pistons contradicting a seller/ racer of the type of piston discussed, (forged). Newbie claims to have had experience although it has been some time and relates more to cars.

Creates a bit of a stir because Racer/seller gets a bit upset his figures are questioned.

Experienced XSer calls out the newbie and dissed him for disrespecting racing/seller.

newbie apologizes for any trouble he may have caused.

Racer/seller accepts apology and apologizes himself

Experienced XSer, accepts newbies apology and goes on to make a point about respect for experience.

Enter another 2nd Experienced XSer, (who has the respect of 1st ExperiancedXSer) and contradicts the racer/seller and states the exact same thing the newbie said about forged pistons.

As a long time forum member i don't know who to believe now so how the hell is a new member going to know. Just because a member is new it doesn't say he doesn't know what he knows. If that person isn't prepared to state categorically 100% he is right, and those long time members, who consider a new member has no right to contradict a long time member, and make the newbie doubt himself and apologize for making a statement, then those long time members should take a step back and take a good look at the situation.

As per forums, the only real thing to do is listen to what everyone says and in the end go back on the net and do some research your self

 

[lakeview]

Given the labour costs to bore and the price of gaskets etc., it really is false economy to cheap out on used pistons. Since you have ordered the 4th oversize, discuss with your machinist if he can do a little taper at the bottom of the sleeve to help get your piston and rings into the bore. They come from the factory with a taper, but with the overbore it will be pretty much gone. Do not worry about your next rebuild and whether you will need new barrels at this point.
This winter I was doing my first installation of pistons into a second over rebore and it was a bear to get the pistons into the bores with the confidence that you didn't mess up and break a land or a ring with all the effort to get them in. Just my experience as a first timer. Equally as hard or harder a task for this first timer was getting the valve spring retainers (collettes? sp) to stay in place and not fall down inside the springs while you unwound the spring compressor. Enjoy your rebuild.

 

[hooser]

Okey now who do we believe. I have never raced an engine, only ridden and done general work on my own bike. So from a laymen point of view, who has respect for Grizld1 and Jack and know Gary has experience in racing and selling XS650 products.

A newbie made a statement on forged pistons contradicting a seller/ racer of the type of piston discussed, (forged). Newbie claims to have had experience although it has been some time and relates more to cars.

Creates a bit of a stir because Racer/seller gets a bit upset his figures are questioned.

Experienced XSer calls out the newbie and dissed him for disrespecting racing/seller.

newbie apologizes for any trouble he may have caused.

Racer/seller accepts apology and apologizes himself

Experienced XSer, accepts newbies apology and goes on to make a point about respect for experience.

Enter another 2nd Experienced XSer, (who has the respect of 1st ExperiancedXSer) and contradicts the racer/seller and states the exact same thing the newbie said about forged pistons.

As a long time forum member i don't know who to believe now so how the hell is a new member going to know. Just because a member is new it doesn't say he doesn't know what he knows. If that person isn't prepared to state categorically 100% he is right, and those long time members, who consider a new member has no right to contradict a long time member, and make the newbie doubt himself and apologize for making a statement, then those long time members should take a step back and take a good look at the situation.

As per forums, the only real thing to do is listen to what everyone says and in the end go back on the net and do some research your self

That was a mouth full but I will go with it. Call JE and see what they recommend. If you can't believe them then do want you want in the end. I can also send you the spec. sheet. As they go up in size they also have more clearance which who make Mean EQ closer to being on the same page. Gary

 

[hooser]

If your gonna run it hard,then .0025 would be to tight,I know of a few people running JEs on the loose side of .006 for insurance and i have a set of Arias pistons that'll be set up loose.006 because of how their ground,etc

Jack we have been setting them up that way for over 10 years and Shell even before that. The 700 is one of my biggest seller and the data sheet goes with them. I can see questioning me as I don.t really know anyone here but why the MFG? I am not talking about a new company JE been around along time. Also the larger we go up the more clearance. Maybe that is why I don't have problems with my motors. I follows instructions/listen to those that know and by and sell quality products. I have Roger to do quality machine work. Along with Auto Rodz machine shop Corry has a nice head machine does all three cuts at once.
Every time I sell something my Business rep. is on the line. Never to my knowledge had a Dis-statisfied customer( as I said to my knowledge).They may not of been happy with the product or I messed up the order but I dealt with it correctly. I have sold on ebay sense 2001 and have had always 100% positive feedback. Lost money making a customer or two happy, but in the long run it has paid off.
I try not to put information on here I can not back up. Once again the specs are JE Specs. Not Mine, Gary

 

[grizld1]

Skull, With due respect to Jack, whom I count as a personal friend, his comment was based on what was done by people he knows and what he plans to do with exotic pistons. My cylinders were bored for 77.5 mm. JE's by Bill Moeller of Bore Tech. Pistons were bought from Shell, if that tells you how long the motor's been in service. We used Shell's recommendation for clearance: .0025", as Gary Hoos says. When I ran a higher compression (~10.25:1) motor with Venolia 77.5 mm. pistons, I used Venolia's spec: .0035". It worked fine, I only went to a lower CR motor because of tense moments with off-the-shelf octane boosters in places where premium gas couldn't be had.

I'll repeat my plea: Please, friends, don't post hearsay! Write about what you've done, preferably with a Yamaha XS650, not what somebody you know has done, or what somebody who knows somebody you know has done, or what specs are for a Rotax 600cc. thumper race motor, or what you plan to do when you get around to it!

With all respect, Skull, you can believe what you want to. There are a few folks on this forum who've ridden with me and who've ridden my machines; proof of the pudding, etc.

 

[grizld1]

Don't know if I was clear or not, so let's try again. If we limit what we offer to what we've done, we avoid generalizations and conclusions that may be inaccurate, misleading, or simply irrelevant. Maybe some JE (or Venolia, or Wiseco) pistons in some motors require wide PTW clearance. No one has stated or implied that such could not be true. But that's not relevant to the point that some specific forged pistons (JE, Venolia) in one specific diameter (77.5 mm.) in one specific motor (Yamaha XS650) do not require wide PTW clearances, accelerate wear, or shorten service life.

 

[hooser]

gizld1 when they don't respect the MFG (JE) setting we are waisting our time..Shell would have just said ok do what you want and never talked to them again. Ist thing I learned when I spent a week with him was Shut the fuck up and listen. So with that being said good luck, if anyone needs good quality, parts go to www.hoosracing.com. , or email at gary@hoosracing.com.

 

[Jack]

For those WHO THOUGHT I might be discrediting their credibility or MFG it wasn't the case only passing on what I know of from other engine builders setting up PWC. Piston forgings have change over years and can be had with or without silicone which can dictate clearances as does piston shape. I bought some old school Arias pistons that require atleast .006 and will set up that way do to the forging expansion rate over a modern JE,Ross,Arias piston. I know of one engine builder who sets his Je's looser than what the manufacturer
recommends without any ill effects.

 

[Jack]

I had no idea there were standard oversizes beyond 4. But regardless, yeah that's my thinking. If I understand correctly, you can safely take 3mm out of the stock liners, so there's room to grow.

Thanks!

There is no room to grow when boring out to 78MM and even at that bore it's iffy as liner distortion could develop.

 

[webbie]

There is no room to grow when boring out to 78MM and even at that bore it's iffy as liner distortion could develop.

I don't mean boring beyond 78. I meant beyond the 76mm bore I'm getting. I just don't want to limit my options for future rebuilds by going straight to 4th oversize on this one. But, as others have pointed out, re sleeving, replacing the jugs, or going to a big bore are all valid options down the road.

 

[hooser]

There is no room to grow when boring out to 78MM and even at that bore it's iffy as liner distortion could develop.

Yes no room to go but once again in all the years never had a problem with distortion . Shell did them long before... how many have you done? I just looked back in this years invoices we have sold over 50 this year, bored around 15 of them so far this year alone. No one is having an issue. Been selling them sense 2006. None have come back, no reports of distortion. Maybe you need a new bore guy.
The worst part is it is hard on the cutters cutting into the stock sleeve that far that is why we had to go op to $150.00 to do the 700. Everything else is $50.00 a hole.

 

[Jack]

Yes no room to go but once again in all the years never had a problem with distortion . Shell did them long before... how many have you done? I just looked back in this years invoices we have sold over 50 this year, bored around 15 of them so far this year alone. No one is having an issue. Been selling them sense 2006. None have come back, no reports of distortion. Maybe you need a new bore guy.
The worst part is it is hard on the cutters cutting into the stock sleeve that far that is why we had to go op to $150.00 to do the 700. Everything else is $50.00 a hole.

Well Gary I guess I'll just shut the fuck up ,don't want to misinform any member of this forum.