SRX 600 questions from newbie

[Jugnut]

A few months ago i bought a SRX600 1XS in semi-project condition. Carburetor was removed, airbox missing, aftermarket exhaust system was installed. In the included box of parts was the original carb, plus a big 38mm Mikuni, and a Yamaha Grizzly intake manifold for same. And, a used head gasket Seller said the previous owner had raced the bike. There was a rudimentary bracket to hold the battery (without a box) and the ignition unit was strapped to the frame with tie-wraps. Not exactly ideal...So since then i've installed the original carb, fabricated an aluminum panel/bracket to hold the battery box (found an original one) and mount the ignition unit. Plus done a lot of general clean-up.
So far, so good.. Since i didn't get the original airbox, i decided to use K&N pod air filters, RC1820 & RC2450. According to their website these are the correct ones. Problem is, they don't seem to fit. I can install one or the other separately, but not both at once. There's not enough clearance between the two to get them both installed onto the carb flanges. Am i missing something?
The other issue is a little more perplexing. A week or so ago i attempted to fire the best up, but had a lot of trouble kicking it through. It was all i could do to ease it past tdc on the compression stroke. In fact i could put all of my weight on the kickstart lever and it wouldn't budge, it required an extra lunge. Yes i'm familiar with the starting ritual for big singles, having owned a BSA Victor 441 back in the day. Seems like it shouldn't be that difficult, as long as the compression release is working properly. I removed the inspection cap for the RH exhaust valve to check it, it seems to be lifting the valve like it should. So i don't know what's going on.. When i got the bike, it had a bicycle pedal installed on the kickstart lever, just like a Harley from the 1920's. I got rid of it because it looked ridiculous. So now i'm wondering if the PO made some internal mods to the engine, like a big bore kit or HC piston, whatever. Apparently he must have had the head off at one point (evidenced by the used gasket)  Anyone have any suggestions?

[iansoady]

Does it turn over easily with the plug out? That would confirm whether it is actually the compression stopping it.

[Jugnut]

Yes with the plug removed it kicks over fairly easily. I could do a compression check, the service manual says it should be from 128 to 171 psi. But that's with a warmed-up engine. So far i've only gotten it to pop & run for maybe a second, on starting fluid. No idea if the carb really functional or not. I just might have to put this project aside for a while.

[themoudie]

Aye Jugnut,

Let us have a ponder, please. SteveL, Andy 230 and SteveH, along with Ian and myself all run these engines and the first two in modified forms.

From a rapid scan, your symptoms point to a potential HC piston and or a badly adjusted decompression lever. You should be able to bring the piston to TDC, bring the kickstart lever to the top of it's travel, then ease the piston over TDC, then return lever to the top of it's travel again, before giving the long swinging kick to start the old bird. Needless to say priming the cylinder with 3 induction strokes of the piston, half to full choke and no throttle, before the final ritual are also important! 

A degree of perseverence could be required after the "racer" has butchered things.

Also, use the "Search" window facility for the forum in the top right of the window, we may already have discussed some of your problems, at length!

Good health and I hope that you enjoy the forum, Bill

[Steve H]

Sound to me like the compression release isn't working that well. It could be the the cam has been replaced with one of higher lift/longer duration, the additional lift is often achieved by grinding the base circle of the cam, this moves the position of the rocker relative to the valve and the additional gap is made up by the tappet screw adjuster. I seem to remember that the new rocker position means the de compressor arm has to move further to work effectively. 
This may not be the issue but it would be the first thing I would check. You could try getting the piston near TDC and then using an adjustable or mole grips to open the decompressor and see if it is easier to move over TDC. This will be easier with the tank off.

[Steve Lake]

our top contributors (steve h, iansody & themoudy) are out in force, and have pretty much covered it all...
however, as you say you have had it 'pop', and 'run for a second or so' on Bradex?. then fuelling is worth a check , are yo using the standard carbs ? if so check the correct operation of the choke, also make sure the carbs are clean, they are a nightmare of galleries tubes & hidden blanks where crud accumulates.

the auto decompressor can be checked quite easily ... with the plug out, kick the engine over (full stroke from fully up) with your finger pulling back on the decompressor lever you should feel the lever move backwards, as steve says this will (should) lift the valve momentarily. also with the piston at TDC and the kick start lever fully 'up'. push the decompressor lever backwards, the should be a small amount of free movement before it comes up against the valve not sure what this clearance should be as i can't find my sodding manual, but within the next 2 mins i have a good idea who will post the required info :-).
oh, and welcome to the madhouse known as TC

[themoudie]

Aye Jugnut and SteveL,

Bit slow off the mark, for which I apologise,    3mm - 5mm is the slack required in the decompressor cable.

Jugnut, if you require a pdf copy of the Yamaha SRX600 manual, please PM me, with your email address and I will send a copy of the pdf. Alternatively, the Clymer manual for the XT600 provides most of the information required.

Good health, Bill