Flat spot

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humanoid1989
Posts: 33
Joined: Sat Sep 04, 2010 4:52 pm
My Bike: kawasaki zxr400 h
Location: Kent/London

Flat spot

Post by humanoid1989 »

Hi just got my bike going after it has been sat for two years and ive got a couple of potential problems:

1) Theres a flatspot around three quarters revs in gears 1-4 (dosent show so much in 5-6) at about 5-6000 revs. I have to open the throttle a bit more and around 7000rpm+ the power kicks in again. Theres no smoke or anything like that from the exhaust. Is it just something that needs some miles to sort out?

2) Pulling away from a standing start the clutch needs to be fed out real slow or i need to give it a fistfull of revs (about 3-4000) to avoid stalling, what would that be then? Again does it just need riding and sort itself out?

3) I only went for a 30 minute ride and the whole thing felt hot, like id blister my finger it i touched the engine. The temp guage was at half way, but it felt hotter than that to me. Coolant is fine, there was no fan coming on- maybe that only works when the temp guage goes to red? Most of the riding in that 30 mins was normal road speeds, though i did get stuck behind a learner going up a narrow hill! :ffs

Apart from that i loved it- it was my first proper ride since buying it last month. f*** me is it quick for a 400- i gotta get used to it, my old Honda CB400SF felt a bit wheezy by comparison (but i loved it till i got this!)

Thanks in advance for your replies!
[color=#FF0000][b][i]"Quit your jibber jabber"[/i][/b][/color]
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humanoid1989
Posts: 33
Joined: Sat Sep 04, 2010 4:52 pm
My Bike: kawasaki zxr400 h
Location: Kent/London

Re: Flat spot

Post by humanoid1989 »

Sorry forgot to say its a 1989 H model.

Also whats the correct revs to have when idling?
Mines going at 2000-2500 rpm any less and it'll stall when cool. Would that help the engine get hot?
[color=#FF0000][b][i]"Quit your jibber jabber"[/i][/b][/color]
Fastforward
Posts: 30
Joined: Mon Apr 19, 2010 12:00 pm
My Bike: Zxr400 h1

Re: Flat spot

Post by Fastforward »

Theres the manual on the main site. Idling rpm is around 1200. It could be a number of things. Check float heights and clean carbs/jets for a start. Float height +/- 13mm i think. Try a longer ride
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humanoid1989
Posts: 33
Joined: Sat Sep 04, 2010 4:52 pm
My Bike: kawasaki zxr400 h
Location: Kent/London

Re: Flat spot

Post by humanoid1989 »

Thanks- i'll check em. Is it possible the fuelling could be too rich or lean? How do i check that?
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Fastforward
Posts: 30
Joined: Mon Apr 19, 2010 12:00 pm
My Bike: Zxr400 h1

Re: Flat spot

Post by Fastforward »

Well what happened to the bike, why was it silent for 2 years? Are these existing problems? Did you try rebuild it? Running too lean will make the revs hang, running too rich will make them drop. - the carbs have air screws under them when mounted on bike, 1 per carb. If you have standard jets "98", you should be fine at 2 1/4 turns out after screwed all the way in. Screwing clockwise "in" makes it leaner, screwing anti-clockwise "out" makes it richer. You shouldnt really go past 3 turns out and 1 turn in. You want a ballance between rich and lean, maybe a tad bit richer. You should turn your air screws in slowly counting how many full turns and half/quarter turns in, and write them down per carb before tinkering. Also does your fuel pump work? New fuel? Tap switched to on?
Fastforward
Posts: 30
Joined: Mon Apr 19, 2010 12:00 pm
My Bike: Zxr400 h1

Re: Flat spot

Post by Fastforward »

Also running lean would make your bike heat up faster. You should go through the h model manual etc otherwise maybe take it to a good guy to diagnose and fix the problems if you cant. Good luck
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humanoid1989
Posts: 33
Joined: Sat Sep 04, 2010 4:52 pm
My Bike: kawasaki zxr400 h
Location: Kent/London

Re: Flat spot

Post by humanoid1989 »

Thanks- i'll give that a try.
Dunno why the bike was silent for two years, i only bought it in August. The previous owner had a few bikes, i guess he used this one only occasionaly.
I guess these things dont always come up on a short test ride- i'll have sorted in good time though!
She deserves it.
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humanoid1989
Posts: 33
Joined: Sat Sep 04, 2010 4:52 pm
My Bike: kawasaki zxr400 h
Location: Kent/London

Re: Flat spot

Post by humanoid1989 »

Heating issues are fixed- a quick radiator flush and some fresh coolant did the trick.
Dunno why i didnt think of that to start with! :wanker
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