'85 GSX550 Engine Advice

[Stelmer]

Hi all.

I'm after a little advice on what to do with the engine. I've finally seen how much smoke it emits now the exhaust system is 100% gas tight. The engine has been a concern for a long time and now the time has come to tackle the issue.

It burns oil when decelerating and accelerating afterwards. Sometimes it's a small blue trail and other times it's a pretty big blue cloud which lasts for several seconds. It doesn't do it when accelerating normally but I did rev it when we parked and there's definitely blue smoke above 8k.

I know the rings are worn and the valves probably need looking at too. Mileage is unknown but estimated around 55k. I'd like to do the Cam Chain too.

Is it worth doing the above or shall I simply swap the engine? It's an idea i've been thinking about for a while as engines are £120ish on Ebay. Another idea was to fit another engine and strip the old one as it'll be a good learning tool. I've done all the other work myself and i've been wanting to expand my knowledge on engine rebuilding (with assistance of course).


I'd get another bike but I simply have more urgent financial priorities. Plus the old GSX is ''me'' and it's one of a kind round here. I'd like to keep it on the road. Frame is powder coated and everything else on it is ok.

What's everyone's thoughts? If I did the work it'd be over winter.

[nowhere.elysium]

I'd buy at least one donor engine, myself. If the GS I'm working on were in worse nick, with a higher mileage, I'd have done so already.

Personally, unless the donor engine was in significantly better nick (i.e. running sweetly, with no untoward noises/smoke), I'd tear down the engine you know works, and renovate everything that needs it. THat way you've got a proven engine, with all necessary repairs/replacements done, so it'll be good for a while yet.
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'10 SV650SF, '83 GS650GT (it lives!), Questionable DIY dash project, 3D Printer project, Lasercutter project

[Ichy]

You can't guarantee that the replacement engine will be any better. If it is just a couple of puffs then I'd ride it for now and keep an eye on the oil level. Start searching for bits to overhaul it come Winter.

Its the rebore that will eat up the money so maybe search for a replacement head, barrels and pistons as opposed to a full engine.
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https://www.metacafe.com/watch/1972097/how_to_behave_on_a_forum/

[finpos]

The unfortunate truth its that once you've taken that engine to bits you'll find every wearing part in it is at it's service limit. Then you need to decide how much of that to replace, given that it will cost 000s to do even if you can find all the parts!

Depends how much the bike is worth to you - the practical option is a second hand engine which looks better than yours and some good luck. Old 4 pots are a money hole.

F.

[truslack]

I'd put a new set of valves in and regrind the valve seats, my mate has a GSX550 which has been abused for the last 30,000miles (its on 90,000) and hardly drinks any oil, your bike is in a lot better condition than his!
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Current: Suzuki RG 125 Gamma, Honda H100, Triumph Tiger 800XC, Suzuki SV650 (minitwin)

[Robby]

If you change the engine, then it would make sense to pull down the new engine prior to fitting to check the condition of the rings, grind in the valves, and fit new seals and gaskets - inc valve stem oil seals, which are probably one of your current problems.

Seeing as you're going to do all of those things, it's worth pull the existing engine apart now. If the current engine is knackered, then stripping it is practice. If the current engine is ok, then stripping it means you fix it.

Are you very sure that the piston rings are shot? In my experience it takes dedication to wear out the piston rings on a 4 stroke, the valves will be covered in carbon and their stem seals shot well before the rings wear. Valves can be reground at home, and stem seals come as part of the £30 pattern gasket kit. You can measure the ring end gap while its all apart as well, so see if they really are worn.

[temeluchus]

Smoking on decelleration is a good indicator of knackered valve stem seals.

New stem seals and perhaps a new set of ring will most likely clean up the bikes emissions.
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Some shite cruiser. Now with guns and FREEDOM!

[Stelmer]

Some useful advice, thanks.

I was advised it may be the rings several times over the years and I do need to do a compression check on the engine. Personally i'm not sure if it was the rings or the valves. I do have a spare head in the garage which I used for the rocker cover mounts - i'll have a tinker with it after I come back from Wales.

I think that before I do anything, a compression test should be done.


I did 170 miles on it yesterday and it didn't use that much oil, despite burning some. It got 53mpg too (14 litres) if that means anything.

[temeluchus]

Stem oil seals shouldn't cost much-when your on the overrun and the throttle is closed, the intake stroke will draw oil through tired stem seals hence smoke on the overrun.
worth replacing if you have it apart for new rings.

Stem seals will be a few quid each, rings will be tenner a piston ish.
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Some shite cruiser. Now with guns and FREEDOM!

[virus]

Do a compression check and note the PSI, then add a teaspoon or so of oil down the plug hole and do it again, If the PSI rises dramatically then you can be fairly certain its rings. Id hazard a guess that a second hand engine would be cheaper than new rings on all 4 pots but as has been said, check your new engine over before paying too much for one.

Cheers
John
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own: 81 xs1100g...
owned: 85 rat CG (sold), 91 GS500e (stolen), 84 gsx400f (scrapped), 81 z250 (siezed, siezed, scrapped), 83 cb250rs (sold), 84 gpz750r ratfighter (killed) 84gpz400 (sold), '80 cb650 ratfighter (wrote off) 95gsx6/12f ratfighter (killed) 91 xj900 (sold)
stinkwheel Well I just had my hands up a pigs fanny. Which makes your concerns pale into insignificance.

[Casper]

If you do go down the 2nd hand engine route those ones on eBay dont look to good. Join oldschoolsuzuki and ask in there.

https://forum.oldskoolsuzuki.info/cgi-bin/Yabb/YaBB.pl