1987 gpx 750 r ninja... hot start problems

[Daphilps]

Hi there, I have a problem with my 87 kawa gpx 750R, after taking her out for a short ride, maybe 1/2 to 1 hr, if i turn her off she wont start unless i wait for 10-15 mins and then away it goes and then only on full choke, it will try and fire but just doesn't start. could a complete clean out of the carbs help out or do i need to look at something like replacing plugs. any help will be gratefully accepted.
cheers
tony

[James Deuce]

Could be a whole bunch of things, but my limited experience hot start issues can be attributable to inlet valve clearances.

Sounds like a carb clean and balance and a valve clearance check may be a good start, possibly reg/rec too.

[TimeOut]

Hi
My son has a 250 with the same problem also after being left for a week or more. Found that switching the fuel cock to prime for a minute before starting solved it.
Don't know if the 750 is the same, it appears the fuel was evaporating out of the carbie (hence the need for choke when hot) the 250 is a vaccum fuel pump so doesn't pump till it is running.
Hope this helps, something to try anyway.

[Daphilps]

cool, thanks guys gives me somewhere to start.

[awayatc]

Hi, if you have fuel and a spark it should run....
If it has a hard time starting when hot, try to eliminate one or the other....Does it get a good spark?, if so fuel supply is suspect....If it gets fuel spark has to be suspect...
Sparkplugs have a limited lifespan...how long before they were replaced?
Easiest test to perform next time it happens...pull out a plug and see if it gets petrol (wet)..
Good luck

[Daphilps]

I honestly couldnt tell you when the plugs were replaced as i have only had the bike for 3 mths, I am waiting on a guy at the moment who is sposed to be giving her a full service including plugs as well as repairing my leaky fork seals, but will take a plug out and check it out in the meantime to see if thats part of the prob. cheers

[F5 Dave]

Hi, if you have fuel and a spark it should run....
. .

erm, typically there is one more factor in that equation. As Jim said Compression: & inlet valves not seating will reduce that.

[Daphilps]

frustrating, been out twice lately for 1-2 hr rides come home and bike starts perfect while hot. Grrr. maybe not as serious as i thought, 1 can only hope.

[Daphilps]

had a bike mechanic do my fork seals as a perky last week and his thoughts were maybe i was getting fuel evaporation at hot temps, will have to wait for a hot day to try it out.

[Cary]

Could be a whole bunch of things, but my limited experience hot start issues can be attributable to inlet valve clearances.

I agree, first thing should be check the clearances.

[Daphilps]

Talk about fucking ropeable, took the 87 gpx to teviot st vtnz dunedin for a wof this morn and it failed, fair enough on the front brake lever not switching on the brake light. a bit unfair that they couldn't find my vin plate,a fail. and then i find out after 13yrs of wof they suddenly tell me its an american import first reged in 1995 and the headlight assy is dipping on the wrong side so another point failed, first and last time i go there.

[Daphilps]

Well......after calming down a bit i managed to sneak away from work early to get up to oamaru where i have my parts bike stored, and although i dont remamber it having a headlight, when i got up there, there was a plastic one (Stanley brand i think) sitting under the tarp, it is slightly different than the glass one but hopefully it might work to pass a wof, then maybe i put the glass one back in. found the vin plate, as per usual it was under the last side cover i looked under, vtnz didnt even take any covers off. and after the mechanical therapy off swapping the lights over i managed to fix my micro switch for the brake lights. now its time to study for tomorrows exam so off to make a coffee.

[Katman]

it is slightly different than the glass one but hopefully it might work to pass a wof, then maybe i put the glass one back in.

If the glass headlight is dipping in the wrong direction I would strongly suggest not putting it back in. (And if you do, don't
ride the bike at night.)

[Daphilps]

If the glass headlight is dipping in the wrong direction I would strongly suggest not putting it back in. (And if you do, don't
ride the bike at night.)

yeah i had decided to leave it out and when i do all maintainence and repairs over winter i'll order a new lamp from aussie.