what is involved in boring a motor

[tc862011]

i am thinking about boring my 550 this winter to pull more power, what is involved in this work, other then the obvious new pistons, rings, and carb work, do you need a different head, do you need to overhaul the original head and how much does this usually cost, rough estimate

[7981GS]

Look in the Projects/Rebuilds section and you will find several 550/650 projects.

Eric

[hampshirehog]

I don't think anyone makes performance pistons any more for the 550.

Probably your best route (bar buying a bigger bike) is to copy what Suzuki Don did with his 550 - put a 650 top end on.

[tc862011]

yea i have figured i am going to keep the good ol 550 the way she was born and get a bigger bike, not going to get rid of the 550 and will still ride her. i might have the pistons bore .50 over just to remidy the old consumption issue but its not horrible so i am not worried. the only time anyone sees smoke come out of the tail pipes is when i gear down and nail the throttle and even then its not alot cause when i look behind me i dont see any smoke, and when i pull the spark plugs they dont look oily or anything, and i know that they sell the .50 over pistons and rings cause i order stock size pistons and rings when i rebuilt the engine and they sent me the .50 over ones instead.
same pistons just a smidge bigger. thinking of it now i should of kept them and just done it in the first place . would of been the smart thing to do, but you live and learn and for the first bike i have rebuit frame up she runs beautifully

[tc862011]

at least that is what the pistons said on them when i got them was 0.50 and they where just a hair bigger and wouldnt slide in with the rings on them

[Nessism]

Did you install new rings when you did the engine before? If so, what size were they? Did you hone the cylinder before installing the rings? Did you replace the valve stem seals?

[tc862011]

i installed new rings and honed the cylinders, i had replaced the valve seals and then i ended up having to get a new head because one of the spark plugs holes had a helicoil from the PO and it ended up stripping the helicoil out so i would of had to go to a bigger hole to go back down to the right size hole and that would of been cutting into the sealing surface of the valves so i found a good usable head on ebay and switched it but completly forgot about the valve seals on that. but i was thinking that since the only time you were seeing smoke was in the high rpms when kicking down a gear 'when passing a car' i figured i was getting blow by

[Nessism]

Were the rings .5mm OS or standard?

I'm surprised you are getting smoke. Were the cylinders pitted or excessively worn? Most GS's are good for 100,000 miles on the stock bore unless the engine was abused.

[lonerider00]

Yeah, personally I would never, repeat NEVER, bore out any engine for power. you're just asking for overheating and other issues when you do that. Only bore out an engine if it's too far gone to hone and you need to get the original clearances back. This was something I was taught in my high school auto shop class about 20 years ago, and since then I have seen (and laughed at) many, many, many people sitting on the side of the road due to their engine overheating and throwing rods because they tried to bore their engine past what it was designed for. Not to mention the fact that boring typically won't increase your displacement all that much, unless you put a stroker kit on it as well (at least for car engines). When I was a jet ski mechanic I did build/ machine down a 550 case to fit 650 cylinders and pistons. the thing ran like stink and didn't have any major mechanical issues. You could probably do something similar to these bikes if you wanted to but I sure wouldn't even think about boring it out; then again, my 550 as it sits gets me plenty fast enough (90+ highway) and is virtually bullet proof, so I wouldn't touch it.

[tc862011]

the rings i put in it was standard, no pitting and the bore job was done very carefully, i did the break in procedure like alot of people on here have explained, not to baby or lug the engine. i have been suspecting the valve seals since i forgot to redo them in the new head. but i didnt think that the valve seals would have that much affect, unless its pulling oil into the engine when it revs up like that, i know when its in the yard i can rev it pretty good and i dont see any smoke, and there isnt any smoke on hard acceleration going up hill or letting the bike decel going down a hill. there is some smoke at start up when it has been sitting for a few hours or over night, which had me leaning to the valve seals, when i tore the engine back down to replace the sucky base gasket i bought and somehow boogered up during the rebuild the pistons and the cylinders looked great. they looked brand new no scoring, pitting or any evidence of the oil control rings being overlapped. any ideas cause when i pull the spark plugs there really isnt any evidence of oil and they all have that coffee with creamer look, as per my dad always says thats what you should be looking for when the bike is running right. i am kinda getting lower gas mileage then last year but its not horribly bad. i dont really want to bore it over cause i have heard when you start doing that then you start running in to more issues then you want to deal with.

[tc862011]

when i put the cylinders back together i tried my damnest to get all the ring gaps the right distance away from each other, and i am sure i did it successfully.

[tc862011]

and when i mean smoke it has to be a very minuet amount cause i have replicated when people say they see the smoke and when i look behind me i see nothing

[Big T]

You were asking about cost- figure $1,000 minimum

[tc862011]

does it sound like the rings still or does it sound like the valve seals, either way i will just wait until the winter to fix it. i have sacraficed enough riding time this year

[hampshirehog]

Unless you have done a massive mileage, it'll just be the valve seals. Especially if you didn't change them last time you had the head off. Those little bits of rubber are getting very old.