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Bike no start

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wurlyvalve

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  • Bike owned: GK73a, TRX850, 955i, ZZR6D

Bike no start

PostMon Jun 19, 2017 9:06 am

Hello all,

A little muddled and complicated this one. And I confess to the weather having made me lose my cool.

I pulled the carbs off to put bigger main jets in. Took the bike for a ride and it seemed a bit too rich at the top end. I rode home and the bike got a bit lumpy at idle. I turned it off. Took the carbs apart and put back to how it was. I started the bike, it ran for a bit - massive back fire then stopped.

Took the carbs back off (repeat this loop about ten times with decreasing enthusiasm and vocabulary) cleaned double checked and refitted. The bike never ran again. In the process I damaged the new litetek bowl seals so they leak a little now :( I've ordered some NRP ones instead as I wasn't too impressed with the fit of the Liteteks.

As a complete desperation action, I checked the spark. No SPARK!!!!! All four plugs wet. There was 12.xV on the coil but no connection to ground. I removed the side stand switch, it's 3Mohm pressed and 3Mohm not pressed. I guess this is goosed?

I don't have a wiring diagram for a GK73a, only a jap diagram for a 76a. So I can only guess at what is intent. I was busy dicking around with sidestand switch connections - which I do know makes no difference in neutral but I was getting quite irate after 7hours in the burning (for UK) sun. And all of a sudden I had spark again. It looked VERY random though. Strong but not ryhtmetic like I'm used to. I reconnected and tried to start again and all I get is the occasional coughing of trying to start. :(

It has new plugs and coils (1month old). Last time I checked it was 30kohm all in.

Any help? I got most disheartened yester, it was my birthday and it didn't feel at all fun!
Ignition pick-up? If so, any suggestions on where to get another?

Cheers,
Glen.
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moforockband

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  • Bike owned: GK73a SP CRM250 mk3

Re: Bike no start

PostMon Jun 19, 2017 10:15 am

Well seeing as it's your birthday.....

The gsxr400 fouls plugs easily, and then will not fire until they are cleaned. Clean them with a butane gun/fag lighter and then wire brush them clean and then blow any debris out. Be mindful though that plugs are ideally only meant to be fitted once ideally as they have a crush gasket, and can snap off if you repeatedly keep screwing them in and out without a tq wrench.
I have 2nd hand pulse coils etc, yours should measure 100 ohms at the plug.
Simply link the sidestand wires together at the main loom end, and throw the switch away. yours is knackered.
There is only a ground when the cdi fires the coil. 12 volts is sat there constantly on the coil.
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wurlyvalve

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Re: Bike no start

PostMon Jun 19, 2017 10:27 am

I had shorted the connections at the bike end of loom (not sensor). Didn't get a spark. But obviously I need to do this now to ride in gear. And clearly it had no ill effect in neutral. But I was getting very irrational by this point.

Yeah, ok, switched ground for the coils.

I'll measure up this afternoon the pick-up coil resistance. After I cycle home :( God, I didn't want be fit and healthy at the ripe age of 42!!!!!!
If not 80 to 120ohm I might take you up on a purchase of your pick up coil. I'll get back to you.

Cheers,
Glen.


For the record, 120MJ's were too rich. Gurgling no pull from 8k onwards.
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moforockband

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Re: Bike no start

PostMon Jun 19, 2017 4:51 pm

Check the 2 pin connector from pick up coil to cdi. Mine plays up occassionally/bad connection.
As said, I'm on 128's dynojet MJ's now with S+B pods, and straight through exhaust. and it's the fastest it's been.
Remember the feeling rich thing can be the fuel reversion/unsmooth air flow that cv's get finnicky about.

I'm 42 and am a noob mamil. I love cycling! :drool:

Nick.
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wurlyvalve

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Re: Bike no start

PostTue Jun 20, 2017 6:58 am

104ohms. So that's not the issue. I'll keep looking!!!!!

I've had the dashpot/slide reverb on another bike I've tuned. Got around that with some sleeved down feed holes on the underside of the dashpot/slide and slightly miss matched springs to prevent all four oscilatting at the same freq/rpm.

This didn't feel like that. But right now my focus is getting the thing to start. I tried to crank last night but she no fire. So I went off and filled a jerry can up. The tank is about to go on to reserve and I wouldn't want to spend an eternity trying to start a bike with a fault that I already knew about! Only a fool would do that..... and I am foolish ;)

Cheers,
Glen.
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wurlyvalve

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Re: Bike no start

PostFri Jun 23, 2017 7:25 am

Well, got the 15month old to bed early last night and sent the wife off for a late shift....... so I had a two hour opportunity.

Carbs back together, still look fine. New NRP seal (I much prefer!!!!) to replace the one I tore in my rage.

Still no spark on the one plug that I had time to get out!!!!! I have 12.5V on the coil. The plug looks dry. I shorted it to three parts of the bike and confirmed with multimeter that they had good continuity to the ground post of the battery.

99ohm across the trigger pins (CDI side). And looking at my multimeter it is pulsing whilst the crank is spinning.

I'll check through the coils and HT leads tonight. But I only replaced them recently.......

Cheers,
Glen.
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moforockband

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Re: Bike no start

PostFri Jun 23, 2017 11:14 am

GO through all the basics again.
- 20 meg through the plug caps and the coil
- Plugs cleaned and gapped
- above 140 psi cold compression
- carbs set up and pilot jet not blocked. You can check the float level with some clear aquarium tubing if need be.

Does it fire up on 3? Make sure you have freshish cr9ek plugs in there, or it will run real bad if they are fouled.
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wurlyvalve

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Re: Bike no start

PostFri Jun 23, 2017 12:32 pm

Yeah sure, one does not get anything like the time one used to :(
Tonight its re-check the coils, then check the igniter for power and ground etc. I've reverse engineered the Japanese wiring diagram that is floating around on this site into English. So now have a slight clue of what is what.

I'd love to check the compression but I rent a small house during the week and the bike has broken down there. My workshop is back in Ipswich 160miles away with most of my tools.

Plugs have done 100miles or less, so fairly new, look pretty clean to me and fairly well gapped.
I can't detect any blockages, all the jets and passages flow fairly well.

Nope, no firing. Nothing. Not on any cylinders.

Cheers,
Glen.
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wurlyvalve

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  • Bike owned: GK73a, TRX850, 955i, ZZR6D

Re: Bike no start

PostFri Jun 23, 2017 3:10 pm

FIXED FIXED FIXED. The CDI/igniter only had one corroded terminal. The earth terminal (actually it was a connector just off it). Amazing the difference having an earthed igniter makes!!!!!

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