Hitchcocks Forum

Hi all I could do with some technical help here, have been restoring a 1963 crusader 250 sport, all was going well until it was time to fire it up, it wont!!!!!! its had an engine rebuild using new and existing parts, a new carb and an electronic ignition. We have a good spark flowing fuel and plenty of compression, every thing points to the bike firing but it wont. has anybody got any ideas? here's hoping, cheers Kram

Timing?

Tried all different timing scenarios!

You say you have fuel flowing but is it getting into the chamber, take out the plug squirt in a few drops of petrol put plug back wait a minute for the petrol to vaporise then see if it fires, if it does then it a carb jet blocked.

the plug after trying to start , is wet with petrol! It’s certainly got 2 of us baffled!

Have you tried different plugs? try wiring the ht lead direct to plug without plug cap, I know you've said it but double check you're on the right stroke.

A good spark out in the open does not always mean a good spark under pressure in the cylinder.

If the likely problems can be ruled out we could be looking at something less obvious. A new carb (Mk1 Concentric? Monobloc?) shouldn't be giving you an air leak problem if you've fitted it correctly with whatever gaskets/heat spacers are needed, and the carb flange on the head isn't damaged or distorted. If you're managing to wet the plug, I'd say not. Carb jetting correct? Float height? Too much choke? Over-tickling? Duff fuel?



But the presence of sparks, compression and go juice (assuming not too much) and still no bang still suggests your new ignition isn't delivering the spark at the right time, as RoSy suspects. Assuming you have got the mechanical side of the ignition timing correct, have you got all the wires connected in the right sequence as per instructions? Worth double checking, if only to confirm that it is not the source of the problem. What are all the different timing scenarios, exactly?



A.

Good spark, fuel (i.e. at somewhere near the correct fuel/air ratio) and compression mean that the engine will start. Period.



If the engine does not start then one of these essentials is not present. That’s obvious. What isn’t obvious is which element is letting you down. And only a thorough systematic check and maybe double check of all factors will give you the answer. Suggestions could be made ad infinitum but you'll find the solution only by checking the bike in question.

Kram, (Mark?) I'm sure you have tried to give all the relevant information to help diagnose the problem but it's notoriously difficult without a detailed description. So, in no particular order: what make 'electronic ignition'? Was the bike a runner before the rebuild? Did you build it from a box of bits? Where did you get any replacement parts from? Did you use a Workshop Manual? Did you use the correct Parts Book for the year of the bike? Have you done this sort of thing before? Sorry if this seems patronising but believe me, we've seen dozens of this type of question and it really helps save time if we have the background. And something practical to help you, there is a Yahoo Group especially for Crusader Owners, most of whom don't come on here by the way, it is at


https://groups.yahoo.com/neo/groups/Cru ... group/info

and is a mine of quality info and advice. Finally, where are you, it might help if another owner is nearby.

REgards, Mark