Bike major problems,Ideas please

[daveb47]

Son has recently bought 1984 Suzuki Gsx750 es bike.

When he got it it was cutting out on 2 cylinders at low speed,cleaned carbs and replaced coils.

Now on 4 cylinders ok but on low revs just cuts out as though ignition has been turned off,then may or may not start again.

Ideas anyone,or has anyone got an ignition module & hall sensor.

 

So pissed off with it now.

 

Or maybe someone has a reasonable priced large bike,he has just passed test and wants to get on road.

[Cavcraft]

I see 'reasonable priced large bike' as 'small, Italian oddball' and am delighted to offer a Cagiva 125 Roadster. Reasonably priced.

 

 

Has the Suzuki got a fuel filter and have you had the carbs balanced?

[daveb47]

He has just sold his 125 Billy.

It has no fuel filter and carbs seem fine,it seems ignition problem to mo revs fine then suddenly just cuts out totally and wont restart straight away.

[Junkman]

Replace the plug leads and it'll run like new.

[John F]

My first thought was fuel starvation, i.e. fouled fuel tap strainer, fuel filter, idle jets in carbs. Specifically check the float valves are correctly set if the carbs have been in bits - that can cause fuel starvation.

 

Is it definitely an ignition problem? If so, check which cylinders are firing using the spit test on the exhaust headers. If it's one coil that's not firing, check its feed wires and also that it's earthing properly to the frame.

[daveb47]

Just had both coils replaced,its running on all cylinders just cuts out totally as though ignition has been turned off.

Suspect its an ignition problem.

It has boyer ignition system fitted.

[Bren]

It's a 30 year old suzuki.

 

I would check the wiring first - you may be horrified at what you find.

[daveb47]

Just discovered that its charging at well over 15 volt and has wrong rectifier bodged in for a start

[Bren]

Its a wonder battery has survived.

[purplebargeken]

Was going to suggest regulator/rectifier, HT leads and caps.

[alf892]

Is there not a fuel strainer as part of the fuel tap?

[Bren]

Usually when the rectifier goes the bike will run until the battery is flat.

 

You can seal the coils with silicone where the lead emerges - beware of non oe plug caps - I have had NGK items that have not been that good.

[twosmoke300]

Complete cut out , I'd be looking at the kill switch , ign and side stand switches . most map bikes use an earth to kill system so if a wire touches earth it stops the engine . Its usually a separate wire on the Cdi unit so try it with it disconnected .

[Cavcraft]

If it's only doing it at low revs I'd personally doubt it'll be the kill switch, side stand or ignition.

[srad34]

Fix it with fire before the rust/electrics kills it.....HTH

[hairnet]

If it's not a Katana, kill it with fire before the rust/electrics kills it.....HTH

[jonathan_dyane]

Have u tried disconnecting the electronic ignition?

[nigel bickle]

Ignition , side stand or kill switch. By pass the kill switch temporaily, disconnect the side stand switch and if those dont 'cure' it, replace ignition switch.

Age is letting moisture in, I'd wager

[daveb47]

Problem believed sorted,It was voltage regulator overvolting everything.

[purplebargeken]

I knowz my old Sukuzi's. It's regulator/rectifrier 99.99999999999999999999999999999999999999999999999999999% of the time lol. 

[John F]

purplebargeken, on 29 Oct 2014 - 5:46 PM, said:

I knowz my old Sukuzi's. It's regulator/rectifrier 99.99999999999999999999999999999999999999999999999999999% of the time lol. 

 

I rewired the stock Suzuki reg. / rect. on my Katana with a Honda one about 14 years ago, I'd forgotten how bad the originals are...

[willswitchengage]

If you only cleaned the carbs then I'd recommend replacing all of the float needles, or at least the two on the errant cylinders. I did it out of curiosity when my bike exhibited the same symptoms on a cylinder, the needles looked in good condition but a replacement cured the issue.

[purplebargeken]

Yeah, Honda one's were the replacement of choice lol. I had a GS850GX (shafty). Brilliant bike. 

[John F]

purplebargeken, on 29 Oct 2014 - 6:57 PM, said:

Yeah, Honda one's were the replacement of choice lol. I had a GS850GX (shafty). Brilliant bike. 

 

I've had two GS650 Katana shafties... a GX and a GZ (although I fitted GZ tank & fuel gauge clocks to the GX).

 

Epic bikes, would have another tomorrow - even in preference to my 1100 Kat.