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what is involved in boring a motor

  • Thread starter Thread starter tc862011
  • Start date Start date
i was thinking if it was the bore it would be showing up alot more then the few times that people have actually seen smoke and i would think it would be more heavy smoke then it is but i may be wrong
 
it wouldnt be a smart thing to do by pulling to new seals off of the old head to put in this one one would it. just thinking about it makes me think they would have a better chance of falling off or not sealing but i figured i would ask
 
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i didnt check the clearences cause with the new rings they slide in real nice it wasnt really tight but it took some careful maneuvering to get it, they didnt just fall right it, it took some light puressure hen inserting the pistons into the jugs. it didnt smoke for a while after the rebuild i want to say it started a couple hundred miles after i finished it, so i am thinking that the seals that were in the head which prob sat a while before i bought it started to break apart. the PO of the head said it cam off a running bike but was parted out do to a front end accident so i am figuring it was off the bike for a while. will replace the seals later in the season and see if that fixes it and if it doesnt then i will send the bike to the shop i use everyonce in a while and have them go to the oversize pistons. i have brought the bike there before, i have done all the work my self. i really hope the new seals fixes it cause i dont want to put the over size pistons in it, hate the idea of having to bore it even just a little bit. the over size pistons are labeled 0.50 oversized so i dont know how much that they would have to bore the cylinders to make them fit
 
Did you bother to measure the piston ring end gap of the top two rings when they were installed?

Eric
 
i want to get this bike in perfect running order, it is almost there this is the last thing, just ran out of winter and lost some riding time this season putting everything back together. would love to have this bike for years and years to come. i think this winter coming up i might get the frame powder coated the original paint it starting to wear this year, it was last year. at least it isnt chipping or anything just where the seat and panels are it has the rub marks from 35 years of use.
 
do you mean when they were installed in the cylinders? because how would you check that.
 
it was a first rebuild for me so of course i made some newb moves, i didnt know you could measure the ring gap. when i installed them tho i looked at the gap when the rings were closed around the piston and i want to say the gap looked like the around the same gap for the points if not smaller then that, there wasnt much gap there
 
i figured they were stock size rings, didnt see any problem with it
 
was just looking in the book for the procedure of checking ring gap, i have no clue how i over looked that but i am 100 percent sure that it wasnt out of spec, the out of spec range is .09 mm and when i looked at the ring when they were going into the cylinder they were well in the spec range. i am sitting here looking at my feeler gauges and the gap was smaller the that
 
sorry you were right when i looked back down at the book i looked at the wrong section it 0.6mm or (0.024in) is the max limit anything after that needs rebore. but i am still 100 percent sure the gap was less then that
 
That service limit is for when you are rebuilding the bike - if the gap is more than .6mm either it needs new rings or a rebore (and new pistons and rings). In reality you can take one of these to bits that isn't smoking and the gap will be bigger than the service limit. So if you are confident that the gap is well under service limit and that you had good bores it'll be your valve seals - 'it's always valve seals on a 550'.

And don't pull the new ones off your other head - chances are you'll damage at least one of them. They are cheap so just get new ones.
 
I doubt the ring gaps are the problem as the cylinder would have to be significantly worn - 75,000+ miles. Most likely the issue relates to the valve stem seals. No big deal. If you can figure out how to replace the seals without pulling the head you will be way ahead, as the gaskets won't have to be replaced then.
 
ok thank you for the motorcycle chat lol, i enjoy talking to people that understand and know bikes, my wife and kids look at me like i have thress head when i start talking motorcycle jargon. i will try the seals since that is the cheapest way to at least start and if by the off chance that it is the cylinders with the low miles (for a suzuki gs) and there wasnt any scoring or pitting in the cylinders then over the winter i will have someone break it down and bore it for the next size pistons, like i said before i think the next size is .050
 
the bike only has 24,xxx on it so shes still got plenty of life in her
 
7981GS said:
Apparently, the answer is NO. :-\\\
"Houston we have a problem."

Eric
Click to expand...

As Ed says, to measure is to know

Before you decide you can just hone and rering a motor, the bore should be measured to confirm it's within spec and round. Then, you check the end ring gap at several heights in the bore in each cylinder

Then, you measure the pistons

That is why the factory service manual has all those pesky specs in it

And, I'm confused- in post #7 you state the valve stem seals were replaced. Did you replace them?
 
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