Guest tryagain Posted October 3, 2007 Share Posted October 3, 2007 Help required from someone who understands the ignition systems on the VFR750F. I have just purchased a 1986 VFR750F but cannot get it started. According the chap I got it from it had a replacement engine fitted, but has not be started since. I have done all the obvious, cleaned plugs, checked fuel pump and that fuel is getting to the engine. What happens is occasional backfireing (loud) when trying to start. Having had a look around online, and finding this site , it seems that the firing order changed from model to model a bit. I was wondering if anyone could tell from the engine numbers below if this might be my problem ? OLD ENGINE NUMBER OF ORIGINAL ENGINE THAT CAME WITH THE BIKE AND HENCE THE IGNITION SYSTEM: RC24E2011506 NEW ENGINE NUMBER THAT IS NOW FITTED AND WON'T START: RC24E2206032 IF THE FIRING ORDER IS THE PROBLEM, DOES ANYONE KNOW HOW/IF I CAN FIX IT. Thanks, Steve. Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted October 3, 2007 Member Contributer Share Posted October 3, 2007 The engine numbers look in order (the replacement engine being from an '88 FJ, IINM), so all that comes to mind is that the coils are not in the right order. It's also possible that the cams have been replaced mis-aligned. Get yourself a Workshop Manual and go through everything related to timing and ignition, I'd say. HTH. Ciao, Link to comment Share on other sites More sharing options...
Guest Posted October 3, 2007 Share Posted October 3, 2007 Can you get the coils from the donor bike. When changing an engine, it's a good idea to bring all of the electronics along with it. Sounds like the pulse generator in the new engine doesn't like the bike's electronics. Link to comment Share on other sites More sharing options...
Guest tryagain Posted October 4, 2007 Share Posted October 4, 2007 The engine numbers look in order (the replacement engine being from an '88 FJ, IINM), so all that comes to mind is that the coils are not in the right order. It's also possible that the cams have been replaced mis-aligned. Get yourself a Workshop Manual and go through everything related to timing and ignition, I'd say. HTH.Ciao, Thanks for that. The coil wiring for the two front pots are on either side of the bike so it would not be possible to mix these up. the rear two are next to each other so i suppose that could be worth a try. thanks again. Link to comment Share on other sites More sharing options...
Guest tryagain Posted October 4, 2007 Share Posted October 4, 2007 Can you get the coils from the donor bike. When changing an engine, it's a good idea to bring all of the electronics along with it. Sounds like the pulse generator in the new engine doesn't like the bike's electronics. Hi thanks for the reply, sadly I don't have the doner bikes electrics. I am getting a spark at each plug, so I assume the CDI and pluse generator are ok. Just wondering if the CDI units might be different, with regards to the timing of generating the pulses ? Thanks again. Link to comment Share on other sites More sharing options...
Member Contributer hondalover Posted October 4, 2007 Member Contributer Share Posted October 4, 2007 Are the spark plugs getting wet? Is it fresh gas? Just trying to make sure you have good fuel for the spark to ignite. I have overlooked the simple stuff before is the only reason I ask. Link to comment Share on other sites More sharing options...
Member Contributer AndrewNS Posted October 4, 2007 Member Contributer Share Posted October 4, 2007 In one of the quotes, someone said the donor bike was an '88. If this is true, you will need the 1988 ignition module as the '86 ignition box is not compatible with later pickup system. The '86's used a pickup on the cams and only fired the coils on power strokes, the later bikes used a pickup on the crank and fired on both power and exhaust strokes. Good luck! Link to comment Share on other sites More sharing options...
Guest tryagain Posted October 5, 2007 Share Posted October 5, 2007 Are the spark plugs getting wet? Is it fresh gas? Just trying to make sure you have good fuel for the spark to ignite. I have overlooked the simple stuff before is the only reason I ask. Hi, Thanks for the reply. Yes I am getting wet plugs, so the fuel is getting to the cylinders. Cheers. Link to comment Share on other sites More sharing options...
Guest tryagain Posted October 8, 2007 Share Posted October 8, 2007 In one of the quotes, someone said the donor bike was an '88. If this is true, you will need the 1988 ignition module as the '86 ignition box is not compatible with later pickup system. The '86's used a pickup on the cams and only fired the coils on power strokes, the later bikes used a pickup on the crank and fired on both power and exhaust strokes. Good luck! Thanks for that. I have had a look on the replacement motor and it does appear to have a pickup on the Top rear of the front head. Does anyone know if the two CDI from the 86 and 88 bikes are direct replacements ? Just wondering if it would be worth buying the later one if it would plug straight in. cheers. Link to comment Share on other sites More sharing options...
Member Contributer rctwentyfour Posted January 21, 2008 Member Contributer Share Posted January 21, 2008 I don't see that you got the firing order that you wanted. It is 1-3-2-4. The left rear cylinder is #1 The left front cylinder is #2 The right rear cylinder is #3 The right front cylinder is #4 Link to comment Share on other sites More sharing options...
squirrelman Posted January 21, 2008 Share Posted January 21, 2008 the '86 VFR had 3 pulse generators......2 on crank, one on cam Link to comment Share on other sites More sharing options...
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