400

The 1990's Japanese market GSX250SSN (GJ76A) and GSX400SSN (GK77A)
William.sn032
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400

Post by William.sn032 » Tue Apr 19, 2022 6:15 pm

Gents ,I've recently bought a 400 Kat, as non runner ,cannot get this bike to run , after a
ultrasonic clean of the carbs ,new o rings , plugs, leads, fresh petrol, engine sparks, ,compression test no probs, sprayed easy start into airfilter engine turns over but will not fire, cannot thank Fossie enough for his ongoing support ,my next step is try another cdi can anyone help?

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Re: 400

Post by Blix » Tue Apr 19, 2022 6:33 pm

If you are getting spark on all four plugs then not sure what else the CDI does Tbh,
400s are a nightmare though, I feel your pain.
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Re: 400

Post by fossie » Tue Apr 19, 2022 9:35 pm

Welcome aboard ..just to bring people up to speed , this poor chap has sunk so low in desperation that he has been seeking advice from me :D :o
So far we have assertained the carbs have been ultrasonically done with new internals by a Suzuki dealer. New battery ( but gets drained daily :x ) new plugs .
New fuel ....tried easy start . New coils ..
I have seen videos of the starting attempts ....and they all are off a 400 turning over and getting slower ...a sound we all know! :twisted: ;)
The plugs are sparking ....
I think we are at the point of borrowing stuff from a working machine to isolate issues .
While the cdi controls the sparking it also detects voltage etc ....

Discuss.....
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Re: 400

Post by fossie » Wed Apr 20, 2022 7:19 am

I received this picture today , just thought I'd share because it's easier to relate to the patient when you know them :roll:

It may just be the angle of the picture .....but you can see similarities between blix's old 400 and this one! :( :lol:
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Re: 400

Post by Blix » Wed Apr 20, 2022 8:37 am

Mine ran fine :D (provided I started it every week)
It’s been stripped of parts if it was my old one, btw it’s the silver one.
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Re: 400

Post by Uncle Bob » Wed Apr 20, 2022 10:03 am

I think we all know with the 400 it's the carbs that give the most issues. If there's sparks I would assume the CDI is OK. I do have a spare CDI (somewhere in the garage), but I would still think if there's sparks then it's fuel related.

Has a compression test been done just to make sure all is OK in that dept.
Does the top end look like it's ever been apart, just is case someone has got valve timing wrong putting it back together.

I did have a FB messenger conversation with Bill and I think the carbs have had the Litetek O ring kits fitted. The kit not fitted was the throttle shaft one as basically that is a complete PITA in my view. However if the throttle shaft seals leak it will draw in air from there which will cause issues.

I assume rubbers are OK between carbs and cylinder.

Float heights are good.

The prime circuit runs through the float and that needs to be checked to be clear right up to the plunger at the top. Bill didn't say if they were. I would take the float out and use brake cleaner (or carb cleaner) sprayed in the each end to make sure it comes out the other end (see image - red arrow is In. While the float is out spray brake cleaner into the carb where the float attaches and check it comes out of the plunger at the top of the carb. I had to do this with the 250 recently, all float orifices were blocked. Also although different design I just did the 1100 that has stood still June 2019 as all of those were blocked as well.
Can you confirm this Bill?
400-prime.JPG
When the Suzuki dealer changed the O rings they did all of them didn't they. I think the most important one is the one under what Suzuki call the Piston Valve - item 6 on this schematic https://www.cmsnl.com/suzuki-gsf400-199 ... l_XYdrMKUk That could get missed by someone not in the know.

If I had to swap something over and I could get them I'd swap the carb over, but not sure if there's many spare sets about - possibly Jimmy had some (Fossie)?

Hope that helps, though might require the carbs off again :evil: let us know how you get on.

Rob

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Re: 400

Post by William.sn032 » Wed Apr 20, 2022 7:08 pm

Hi Rob,

Who said Burn 🔥 it...lol...I decided to a compression test for peace of mind,which is retuning 150 psi from each cylinder.
The top end doesn't look like it's ever been touched tbh,I can confirm that the carb rubbers are all good .
I remember our previous discussions about the floats Rob, I did personally make sure they were all clear, however I'm waiting for confirmation about the O rings from Cupar motorcycles who are a Suzuki dealer, they completed the ultrasonic clean and fitted the O rings as suggested.
I really appreciate the support from everyone, It's truly appreciated......Guys...

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Re: 400

Post by pookie » Wed Apr 20, 2022 7:29 pm

As Uncle Bob says with the 250 / 400cc bikes the carbs are normally the root of any problems, the viton kit is a must have purchase, it might be a long shot but when I first owned my 250 it was a bit of a pig to start, it turned over for ages before firing up, the problem was a tiny hair width split in the rubber vacuum pipe that goes between the cylinder head and the fuel tap, apparently air was being sucked into the pipe and it reduced the compression needed to suck the fuel from the tank to the carbs, a new section of fuel hose and it started on the button, its worth trying anything just in case and it's worth persevering because when these little kats (kittens?) work properly they are the most fun you can have on two wheels (had my 250 eight years now :shock:)

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Re: 400

Post by William.sn032 » Sat Apr 23, 2022 2:39 am

Hi Pookie.

Thanks for sharing that I'll check our the vacuum pipe.
I've just had confirmation the the O rings in the Piston values were changed and the float levels all checked prior to rebuild.
Would anybody have a photo of the original cdi they could share,I believe my current one is a aftermarket ?

Thanks again for the help Gents, it's all appreciated.

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Re: 400

Post by William.sn032 » Sat Apr 23, 2022 2:49 am

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