itsafive Posted June 10, 2013 Report Share Posted June 10, 2013 (edited) My bike is an 05 250 Pro. Bought secondhand it has always been a pig to start, especially when hot. Things are slightly better after the following work... Cleaned carb thoroughly, several times. New plug about four rides ago. All fuel filters cleaned (petcock and carb). Rewired and lengthened CDI earth lead as poor wiring at chassis connection. Renewed air filter rubber connection as misshapen with age. At yesterday's Loughborough trial it behaved as is usual - get it up to operating temp, stop at a section to look it over (or queue) and bike won't start. Have to use choke and a big handful of throttle and loads of kicking. Had someone else try kicking and it was hard for them too. Sometimes when it's hot you can kick it over several times and it feels like there is little/no compression. It happens even if you get the piston up top before giving it a good kick. Took plug out. Pretty black and recess near the electrodes full of carbon! I have had suggestions of sticking float needle leaving bowl empty and possible crank seal leaks. Any thoughts? I take it that crank seal replacement is a case apart job? Edited June 10, 2013 by itsafive Quote Link to comment Share on other sites More sharing options...
mjb Posted June 10, 2013 Report Share Posted June 10, 2013 I had the same problem with my 05 300 Pro. More than likely its the same problem the stator. It will start fine but when the motor heats up the wires break down. I tried so many things before i got to that conclusion, ht coil, pick up jetting etc I would advise speaking to Steve at Motoplat. I sent him my stator in the post and he re-wired it and sorted the problem. Steve is an english guy but now lives in spain so just be aware if you phone him. http://www.uk-motoplat.com/home.html I sent it orignally to West Country windings but they made a couple of hashed attempt at re-wiring. I guess if you want to be sure its the stator if you've got a mate with the same bike maybe do a swap and see..... fairly sure it is though.... Quote Link to comment Share on other sites More sharing options...
mjb Posted June 10, 2013 Report Share Posted June 10, 2013 (edited) Does it run ok apart from the starting problem? Edited June 10, 2013 by mjb Quote Link to comment Share on other sites More sharing options...
itsafive Posted June 10, 2013 Author Report Share Posted June 10, 2013 It runs just fine one it is going. Ended up doing the last two laps without stopping the engine to avoid having to re-start it! Quote Link to comment Share on other sites More sharing options...
dombush Posted June 10, 2013 Report Share Posted June 10, 2013 (edited) Hi itsafive If it were me i would probably check the simple and basic things first before spending much money. Check your oil mix ratio is something sensible (i use 80:1) Check if the engine cylinder (not clutch) rattles, especially at tickover. Check the compression, expect something near or over 150PSI after 5 kicks, throttle fully open. Take the exhaust header pipe off and inspect the piston for significant blow by (carbon below the rings) Clean the plug. Check the plug gap against spec Kick the bike over when warm and look for a strong spark with the plug earthed. Clean the carbTake all the jets and idle screw out and blast with an air line. Check the pilot jet isnt partialy blocked Check that the jets fitted are to spec. Set the float height Set the idle mixture screw Check the ignition timing is set to the standard marks. Check for splits / air gaps around the carb intake maniufold rubber. Look down the intake rubber with the carb off and look for broken / damaged reed petals. Dom Edited June 10, 2013 by dombush 1 Quote Link to comment Share on other sites More sharing options...
lineaway Posted June 10, 2013 Report Share Posted June 10, 2013 If you really believe the bowl is dry, just throw the bike on it`s side till it comes out the overflow! Then kick it. Quote Link to comment Share on other sites More sharing options...
itsafive Posted June 10, 2013 Author Report Share Posted June 10, 2013 If you really believe the bowl is dry, just throw the bike on it`s side till it comes out the overflow! Then kick it. Not convinced that the bowl is dry tbh. Took ignition side cover off to find a very damp environment! More evidence of electrical issues? Quote Link to comment Share on other sites More sharing options...
sting32 Posted June 11, 2013 Report Share Posted June 11, 2013 (edited) actually, wet doesn't seem to bother except if you have it grounding out with water droplet in the right place? magnet sends ignition pulse out the wire on the "pickup" or sensor, the windings produce electricity that does everything else. weak spark is not uncommon on these bikes, I use a CHEAP flimsy business card to gap the sensor to flywheel, can help spark, water in there means you probably have too tight bolts on cover which can cause it to distort and leave gaps on bottom, OR water getting access at the grommet on top of flywheel area on the case. put some silicone sealant where the wire's sleeve (insulator) goes through the rubber grommet, into the case, so water can't get in easily, IMHO Im talking about sealing the insulator for the wires, IMHO don't seal that up into all the wires. this way, it can act like a vent if you just seal the insulator where it touches/passes through the grommet, I think so anyhow, so that is what I do. Another hot start thing I had, was lean jetting on the bike for your particular altitude. I exclusively ride my 300's in 1000ft elevations, year round. When I had bigger jets the bike starts easier... IMHO. I have leaned my newer bike a "size" on jets, and it now too starts IMHO again slightly harder HOT. So I just rock the bike a couple times, in gear, charge cylinder a little extra fuel, starts about same when I do that. Winter time, doesn't seem to affect me much. Im not positive, been 4 bikes since I had the Delorto on my engines, you probably should see what others are using in your clubs, or your event you are riding, at least? Edited June 11, 2013 by sting32 Quote Link to comment Share on other sites More sharing options...
itsafive Posted June 13, 2013 Author Report Share Posted June 13, 2013 The compression is about 135 psi when cold and 120 when hot. Photo of piston and rings thru exhaust port here... https://www.icloud.com/photostream/#A4532ODWjtzxv Quote Link to comment Share on other sites More sharing options...
dombush Posted June 13, 2013 Report Share Posted June 13, 2013 I'll measure mine in the morning. Dom 1 Quote Link to comment Share on other sites More sharing options...
dombush Posted June 14, 2013 Report Share Posted June 14, 2013 ok 170 PSI cold, 5 kicks, wide open throttle. 2006 250 Pro, std compression.. Piston and rings 4 years old but in good condition. that's quite a bit more. If I were you I would :- Measure the squish with soft solder before dismantling anything. Check against Std (1.3mm) if its considerably more this may be reason for low compression. If the squish is ~std you need to look further, e.g. take the barrel off Measure the ring end gap vs. Std normally around 0.5 - 0.8mm .Worn can be considerably more. Measure the ring width around at 6/8 places to see what wear there is. (should be within 0.05mm) Measure the piston to bore clearance (need the tools) Dom Quote Link to comment Share on other sites More sharing options...
itsafive Posted June 17, 2013 Author Report Share Posted June 17, 2013 Thanks for your help. Great community spirit! I checked the squish which is spot on at 1.5mm. Before I took the barrel off and potentially go even further I pulled the flywheel off and there was a distinctly oily smell with some oily deposits on stator. Also found what looks like emulsified oil in bottom of crank seal. See pics on link below: https://www.icloud.com/photostream/#A4532ODWjtzxv So likely crank seal compromised? Quote Link to comment Share on other sites More sharing options...
dombush Posted June 17, 2013 Report Share Posted June 17, 2013 The slightly bigger squish (1.5mm vs. 1.3mm) could explain the lower compression. Yes, this could be a crank seal but crank seals normaly cause erratic higher tickover due to weak mixture. Do you have this? The degree of emulsified oil on the cotton bud isnt huge for a blown crank seal either. Ive opened up the flywheel cover and found oil / mess all around the bottom of the cover and the bike was still basicaly running (although eratically). Do you think this could just be residue grease from the original assembly? Going back to your sometimes lack of compression when hot..... mine could never be acused of this (hefty kick required always). Although your squish is larger (lower compression), as a guide i cant kick mine without hoisting myself to put full body weight through the kick. The idea of kicking mine over with a simple jab of my right leg is a dream. Dom Quote Link to comment Share on other sites More sharing options...
itsafive Posted June 18, 2013 Author Report Share Posted June 18, 2013 Thanks Dom, Mine has very low compression feel at times. Barrel off and measure rings is next I think. Would I reduce squish with a thinner base gasket or would worn con rod bearings cause this? Quote Link to comment Share on other sites More sharing options...
dombush Posted June 18, 2013 Report Share Posted June 18, 2013 Squish (compression) is a very personal thing. Originally I had mine at 1.1mm and the bike was very (very) urgent in its throttle response. I liked this but the trade-off was lack of smoothness at steady revs. Now at 1.3mm its a happy medium, good (not electric) throttle response but smoother. I can imagine that 1.5mm is very subtle indeed. Worn big end or little end bearings would have been very evident with significant rattling during running. Did it rattle badly? Dom Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.