Waddy92

Thanks for the replies. I manually wigggled the points to see if the left point sparked the left spark plug and it did. I'm pretty sure the coils are wired to the correct side. When I tried swapping them over i got the exact same issue. Do you think it might be a valve issue?

Hello all, This is my first bit of content on here, but I have been a silent voyeur for a while. Lurking in the shadows, trying for the life of me to understand why my bloody bike isn't working. I have taken on a lot of info and tried fruitlessly to solve the issues, but there's something not right. Its a 78' xs250, SOHC, of course. I completely took it to pieces, down to every last bolt. Did everything I could right, all the engine cases got vapour blasted, new stainless steen bolt kit, new gaskets, fresh everything. New coils, new, condensor, new timing chain. But my bike just doesn't want to go. I had an engine, that had a broken kickstart journal (laughably standard issue I've heard), took me ages to solve that kickstart issues, until i realised that I was missing a little shim, which apparently is the make or break between the splines engaging or not. Then my kickstart spring broke. So I've got a brand new one of those also. So after the usual bottom end problems, confusions (this is my first engine rebuild after all), I'm on the top end. Rebuilt the bike, got it all looking nice, kicking over well, and I'd spent a lot of time making the bike look how I wanted. Slaved over every largely irrelivant detail, until I was 95% finished. Went to breath some life into it, nothing; and my once perfect world came crashing around me. Checked spark. Yes Checked fuel: Yes Checked compression: No. Well 75psi Checked carbs: Air Mixture Screw Snapped Life was bad. So what steps did I take to rectify this nightmare. Well, a mate of mine had a spare engine, also with a broken kickstart journal. It was a runner, I know, as I'd seen it running. So he kindly offered me the top end at mates rates. Yesterday, I took the barrel and pistons off my bike, took the barrel and pistons off his spare engine, and put them on mine. Bolted the head back down, timed up the cams (I hope correctly, LT mark on bottom, timing mark on end of camshaft at 12o'clock), and tried again. Compression was at 110psi. Checked it on his bike, which has a working engine and the Halfrauds guage read out 100psi. So even if 110 seems a little low, the reading is 10psi higher that his working engine. Here's my symptoms, and I'm hoping someone can help me get this show on the road. I timed the points with the rigged up light method, making sure the light comes on just before the LF mark and same on the right. Start kicking away like Billio (I'm running kickstart only), and I'm getting little to nothing, even with EasyStart squirted into the barrels. Once I open the throttle, opening the butterfly valves, I get two pops, and even at one point flames and smoke coming out of the cone filters (I must point out, I was using his carbs, as mine are goosed, took delivery of some practically new ones last night). The jets are #122.5, so should be about right for this set up. What is happening?! Everyone I speak to who knows about bikes says timing. But which bit? Points? Valves? Why is there seemingly no life, and then loud bangs flying out the carbs? Is the head wrong? Do I have a valve problem? Any and all insight would be much appreciated. Thank you Waddy

Fixed it. Spacer.

I almost bought a new engine yesterday for £100. A runner, just to I could do a bit of dismantling and see what the difference was between that and mine. However, being a tight sod I bought a kickstart mechanism instead for £15. So I'll try fitting that and see if it makes any difference. The only thing I can think of is that with the extra grunt required to turn over a fully timed engine, the mech is becoming dislodged, and that's why its jamming. Without the rocker cover on, I can kick it over, and depress the kickstarter by hand. With the rocker cover on I can't. SO WEIRD! Does anyone know the right size for the washer that goes between the retaining circlip and the side cover? I don't seem to have one, so I may need to lathe one up.

not tried with the clutch in yet. Is it possible because the engine has no oil? Does that make a big difference?

On the end of the CAMshaft the little pip is pointing up, when the LT mark is lined up. When I turn the crankshaft the engine turns over absolutely fine, there is no compression as I have the spark plugs out. If its 180 degrees out, will the valves still miss the pistons? Unless of course the magneto has been put on 180degrees out? So that the 'LT' mark is wrong. is that possible? And is it right that part way through the cycle, two valve springs are compressed simultaneously? No, I think that the magnet can only be in one position.... must be a kickstart mech issue.

Hello, I am said friend in question. I too am suffering severe emotional trauma with this frigin kickstart! As Kon said, I built the entire engine up only to find that when I went to push down on the kickstarter it locked completely solid. I thought, "Oh sh1te, I've done the timing wrong", but nope. I could turn the engine over by hand on the crankshaft as many times as I want. I gets a little bit stiffer when the two valves are depressed at the same time, but apart from that pretty smooth. so I took the engine to pieces again, as I thought that there has to be something fundamentally wrong with the gearbox. Took it all to pieces, checked it all, compared it to another gear box that I have, and it is exactly as per diagram. Put her all back together again, although I haven't torqued everything down fully until I know it works, just nipped it up. So at this point I knew that it wasn't a bottom end problem, the issues only start when the whole engine has to turn over. So it was a case of the old process of elimination. Firstly I removed the rocker cover, so that the valves were no longer engaging, but the cam shaft was. GET THIS! It works. So I can freely turn the engine over with the kickstarter. The kickstart mechanism turns the gearbox, which in turn rotates the clutch basket, which turns the crankshaft, and rotates the cam shaft. I can do it by hand, virtually no difficultly in turning the engine over. BUT! Once I put the rocker cover on, i.e the valve springs are engaging with the camshaft, it locks completely solid. I can hang off it. It's not stiff, its locked. So the only think that I can think is happening is that as soon as a bit of pressure is applied back through the engine by the valve springs, something somewhere is pushed out of alignment, or disengages, or locks. ONLY when the rocker cover is put back on. Again, I can turn the engine on the crankshaft, but not with the kickstarter. Is there some kind of fundamental requirement for perfection on the kickstart mech. It seems a pretty simple and rudimentary design. How can it not be working? Is it lack of oil, is it spring pressure, do I need to kick the sh1t out of it?! WHAT IS HAPPENING?!!!