Baffling seizure SRX 600

[guest1974]

Hey all, long time no speak! This is Lee (Leah) with the SRX 600 I was out and about on couple of years or so ago. Need some ideas/advice because I managed to seize it proper last year. I assumed I'd let the oil run dry as there was nothing on the dipstick.  :-[Time and commitments meant it got put at the back of the garage until this week when I finally got around to stripping it down. When I drained the oil there was about 2 litres of thick black stuff but no metal in it?? it was still solid when I started, but having got the rocker cover off, finding aluminium scraped off the bit  where the middle of the cam sits (sorry, don't know technical words for 4 strokes), it actually freed off. Removed head and barrel, piston is scored front and back but liner looks ok. The crank flywheels/balance wheels? show bluing heat damage in the area where the conrod is closest to the edge of them - top of the throw.

Anyone have an idea what's happened here? I will replace the piston and rings, also the camchain, but should I look at the oil pump? If so where is it, how do I get to it? Do I need to take clutch and or generator flywheel off? Engine out to split cases?

Any advice appreciated here. Cheers

Lee

[themoudie]

Oh bother! 

From the catalogue of woe that you have described I would suggest that removal of the engine from the frame and a complete strip back to bare cases will be required.

Your comments "finding aluminium scraped off the bit  where the middle of the cam sits" (central cam journal), "piston is scored front and back" usually associated with a lack of oil and "The crank flywheels/balance wheels? show bluing heat damage in the area where the conrod is closest to the edge of them - top of the throw." would indicate that the oil supply to the big end has also been compromised; either due to failure of the oil pump or due to sludge build up in the oil ways preventing the flow of oil to the big-end! 

I would be looking to have to replace all bearings in the motor, have the big-end dismantled and checked, a new oil pump, a new piston and rings and have the bore checked and re-bored by a knowledgeable engineer, either find a replacement head in good condition without the central cam journal chewed up or have your head machined and a new journal inserted and the cam checked for correct dimensions. Whilst your at it, check the cam drive sprockets, chain and guides for wear and replace any component that doesn't match the specs.

SteveH' site SRX600_website has all of the specification data and part numbers that you require.

Alternatively, you may choose to scrap the motor and try to source a SRX400 motor, another SRX600 motor or an XT600 or XT600E motor, all have been put into the SRX600 twin shock frame. BUT! ALL SECONDHAND MOTORS WITH AN UNKNOWN HISTORY CAN BE IN THE SAME CONDITION AS YOURS WAS BEFORE IT SEIZED, THESE MOTORS ARE BETWEEN 25 - 30 YEARS OLD, RUBBER SEALS PERISH AND IF UNUSED, CARBON PARTICLES/SLUDGE FALLS FROM SUSPENSION AND IS DEPOSITED AS "TREACLE" IN THE SUMP AND OILWAYS AND THEN SOLIDIFIES! CAVEAT EMPTOR! Any old motor that has been standing, even with clean oil and a new filter can suffer a 'heart attack' if a sludge clot has formed during its inactivity! 

If I have missed anything or others think otherwise, I am sure I'll be told. As for reliable engineers? Slipstream engineering in Kent would a first port of call, but quality always costs! There are others as good but I don't have their details to hand.

My commiserations, Bill

[guest1974]

Thank you for your comprehensive reply Bill. Oh dear! This sounds expensive! I'll get in touch with the engineer you mention and get them to look at the barrel, head, camshaft and crank.
Other than that I'm happy to do the complete strip down and rebuild. The oil did look sludgy though only covered afew thousand miles on it. Before I got it the bike had been standing (in boxes!)so I feel a bit vindicated that I didn't commit the rookie error of letting it run dry. But I know I should have drained, flushed and put new oil and filter in shortly after I got it running again - learnt that the hard way 

It was getting rattly (oil starvation probably), and backfiring a lot too towards the "end"...do you or anyone know I tune the carbs to stop this? It can't be normal...can it?

All the best

Lee

[themoudie]

Aye Lee,

The rattly bit, as you assume, was likely due to the lack of clean lubricant!   

Your second comment "and backfiring a lot too towards the "end"..." could indicate that there was an air leak either between the exhaust header pipes and the cylinder head or elsewhere in the exhaust system. Another scenario could be that there was an airleak between the carburettors and the cylinder head due to the rubber carburettor mounting sleeves perishing. This would have contributed to a weak mixture/overheating in the cylinder head/piston area and wouldn't have been helped by the reduced oil flow/pressure!

If you intend to put the engine refurbishment the way of Slipstream, before going further I would ask for a breakdown of ALL likely costs and also have them take a look at the carb and mounting rubbers.

There maybe other competent engineers near where you live, but you would need to ask about or speak with others on this site.

Finally!  Before going any further, 'Select' the 'Bike Problems/Questions' section of this Forum and then type in "SRX engine" into the 'Search' box in the top right-hand side of the sites screen. You should be rewarded with a list of 127 threads, all pertaining to various SRX engine failures, ailments, etc and their rectification, I would suggest that you take some time to read this small encyclopedia and take things on thereafter. 

All the best and I hope that you are able to get the beasty running again.

My regards, Bill

[guest1974]

Thanks for all that great advice Bill. I will most certainly do that. On reflection re the backfiring, one of the nuts on the RH header was missing, must have vibrated off at some stage. Wondering if that's the source of the air leak? The carb inlet rubbers look ok but ill get them checked out. I fully intend to get the bike running again, I don't give up easy.

Cheers

Lee

[timbo]

Sorry to hear about your engine blow up, and as Bill says, there is tonnes of SRX info on this site, but you might have to trawl back a bit to find it