any b25 aficionado out there near worcester park s.w london willing to visit and try getting my b25 going. got a spark got petrol just wont fire up. never had this trouble before. more than willing to pay for time.
hi. had a similar problem to my b25 starfire. make sure your contact breaker is fitted correctly, and not shorting out to the base plate.
fitted electronic ignition; checked valve and ignition timing several times; petrol getting through; good spark; will only fire up with a squirt of high octain carb cleaner; lots of kick backs; banging in exhaust indicates to far advanced but retarding not solved problem; just will noy start on normal settings;
Have you tried a new spark plug?
I'm not local I'm afraid.
Did you use the timing tool to hold the crank in place?
Was just wondering as there are two holes the pin can drop into. One is TDC and another at 37 degrees BTDC. I wonder if the pin was in the wrong one when you set up the EI.
new spark plug;new carb;used the correct timing plug;lots of bad language etc
Hi,
Just a couple of random ideas that may be bit far fetched but is it timed on the exhaust stroke rather than the compression stroke and was the engine turned the right way to set the timing? I say this because over the years I have done both of these things.
Dave.
Just another thought. You mention a new carb. Did you strip and clean it? New ones can have bits of machining debris in them as I found in a recently fitted Amal Premier Conc.
Check you have the pushrods the right way round
timed on the compression stroke;cleaned carb;push rods exact length according to rupert ratio,front inlet rear exhaust
engine turned the right way anticlockwise;
Hi Rookey,
It looks like you have tried just about everything and you must be getting a bit frustrated. One last last thing and shout at me if you wish. Engine turned anticlockwise (forward) looking at the primary side I presume?
Again, I have in the past due to being in rush, timed an A10 backwards.
Dave.
I sympathise with you. It is do frustrating. No-one has mentioned the coil yet, could be suspect?
I can't think of anything else that hasn't been mentioned, other than check and double check. It could be a fault in the EI system, unlikely but if your're 100% sure of everything else.Without swapping out one part for another I dont know how you would check.
Keep going you'll crack it eventually.
A good spark was mentioned, however it could be nonexistant under the higher pressure in the combustion chamber. Swapping to evidently working parts is probably the way forward.
You said that "will only fire up with a squirt of high octain carb cleaner" could it be that you have stale petrol?
I think that your problem is carburettor related. A number of people have been complaining of problems with new carbs. Inspection and cleaning seems necessary.
Just to get a bike running, ignition timing is not that important. My Manx starts happily with any timing between 40 degrees BTDC to 12 AfterTDC.
Do you have a fully charged battery? Some EI units will fire too advanced if the voltage is low.
Cheers,
Bernie
As you have fitted EI just check the manufacturers data for spark plug gap. I fitted Electrex World to my SS90 and they state 0.4-0.6mm plug gap which is smaller than the plug gap for points ignition.
Good luck, Colin
I think the non starting will be due to the new ignition unit. Could you fit the original system and then try starting the bike. I had electronic ignition on my Greeves Silverstone and it was wired with a large and small spade connector so it was impossible to connect up wrong. However the unit gave all your symptoms.I was told the unit ran clockwise or anti clockwise. Very frustrating. Dennis
many thanks to all who have offered suggestions it is much appreciated. As i have plenty of time on my hands i have now totally stripped engine down and now in the process of checking each individual part to make 100% sure everything is correct .waiting for new gaskets in the meantime. By the way anyone know where i can get a CORK chaincase gasket.
I don't know about a cork gasket, but I find that a paper one with a good coating of Wellseal on both side works for me.
Assuming of course that your mating faces are in good shape.
HI THERE, THIS MAY SOUND OBVIOUS BUT IF SAY THE CYLINDER HEAD IS NOT FLAT OR GASKET LEAKING GASES > I WOULD DO A COMPRESSION TEST WITH A GAUGE JUST TO BE SURE , ALSO CHECK AMMETER READING WITH EVERYTHING SWITCHED OFF EXCEPT IGNITION AND CONTACT POINTS CLOSED IF THE READING SEEMS HIGH SAY 10 AMPS IT COULD POINT TO A FAULTY COIL AS I HAD RECENTLY ON MY TR25W , IT SPARKED OK BUT WOULD NOT TICK OVER THAT WELL ON VERY LOW REVS AND CARB WAS OK . ALSO CHECK HT LEAD INSULATION IS OK AND FRESH FUEL PREFERABLY 99 OCTANE , I WOULD ALSO CHECK CARB FLANGE FOR WARPING INCASE ITS DRAWING AIR OTHER THAN FUEL . TRY A LITTLE FUEL DIRECTLY IN THE SPARK PLUG HOLE TOO . REGARDS JOHNBOY .
Thanks for all the replies,very much appreciated. decided to strip entire engine down to examine everypart making sure part numbers and dimensions are correct. Will let yo know how i get on. regards to all.
I would endorse what Colin SS90 said, I had a similar problem, changed everything in sight several times with no result. Drained the tank and put some new 5 star in and it started immediately.