750k wont pull at low revs

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jordihutch
Posts: 10
Joined: Sun Jul 29, 2018 11:58 pm
Location: Fife , Scotland .

750k wont pull at low revs

Post by jordihutch »

Hi , first post on forum . From Fife , Scotland , I am at my wits end with this , looking for any help . I have had my GT750k for over 3 years . When I first got it it had a Very loud 3 into 1 on it [ bike came from America ] it was running very rough at low revs but eventually took off around 4000 rpm . Over the last 3 years I / we have tried everything possible to fix this . The engine has been totally rebuilt , crank .pistons ,water pump , gearbox parts etc ,too much to list . The cabs have been off / cleaned replaced about 10 times by me & 2 others . I got a set of Higgspeeds for it , full original air box & put jets back to standard as recommended. It has a Newtronic ignition on it . The tank has been professionally cleaned & coated , petcock is new /seems to work . New plugs , caps ,leads etc & battery . Probably tried a lot more than I can remember right now and the bike is running little better than it did when I got it . It starts ok , can rev up not bad standing in garage . But out on the road it wont rev / pull at lower revs [ almost unable to ride it ] It still takes off around 4000 revs as it did when I got it . I have looked at hundreds of posts on forums etc and not found anything exactly the same . Can anyone suggest what I am missing here ? Although the carbs have been striped & cleaned could something be missing or wrong inside ? Sorry for long winded storey just trying to get some things out the way that have been done . Please can anyone help with this ? trying to recapture my youth but running out of time at 61 now lol.
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canaletto5
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Joined: Tue Jul 23, 2013 8:43 pm
Location: Derbyshire

Re: 750k wont pull at low revs

Post by canaletto5 »

Hi

Welcome!

Have a look at this link to Higgspeeds website. You may already have seen it

http://www.higgspeed.com/FREQUENTLY-ASK ... TIONS-FAQ-

Do make sure your airbox set up is spot on to standard and in perfect condition or you will have problems with standard jetting. What condition are the plugs in? Do they look too lean or rich etc

Good luck

Kev
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BAZ
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Location: Dudley west midlands
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Re: 750k wont pull at low revs

Post by BAZ »

Just a thought did you balance the carbs if so how, and did you put the slides in the correct Bodies.. Have you done a compression and suction test!
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canaletto5
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Location: Derbyshire

Re: 750k wont pull at low revs

Post by canaletto5 »

PS

Baz is the kettle carb guru so you could do yourself a favour by getting him to rebuild and tune your set ;)
jordihutch
Posts: 10
Joined: Sun Jul 29, 2018 11:58 pm
Location: Fife , Scotland .

Re: 750k wont pull at low revs

Post by jordihutch »

Hi ,Thanks for the quick response , but It had the same problem before the Higgspeeds were fitted . All carb settings have been tried . Fitting foam filters , bigger jets etc seems to make little difference to how it runs . This is the problem , I am completely stumped as to what is causing it . I think I have tried everything , but could be something simple I am missing . Everyone says Carbs , but they have been done over and over again to no avail .
Roger Ackery
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Joined: Wed Jul 20, 2011 3:40 am
Location: Sydney NSW Australia

Re: 750k wont pull at low revs

Post by Roger Ackery »

Hi, I know you said it's a K model,are the Carby slides all rising & falling at the same rate ?
Have you checked for air leaks past the inlet rubbers,pods fitted, or standard Air Cleaner ? Have you tried a known good set of Carbs from another bike ? How are the float levels,fuel tank & tap clean ! is the petrol cap breathing ok ?

How are the electrics maybe a fault with the ignition ? Does it start easy & idles ?
I can't think of much else to try or look at.
See what other people suggest later on here :tw
Cheers.
Roger
GT750A.
Kettletimes3
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Joined: Thu May 03, 2012 12:58 am
Location: Sunny Wales

Re: 750k wont pull at low revs

Post by Kettletimes3 »

Is the porting standard on this engine.
If everything else is good maybe someone has been playing with the pot timing.
jordihutch
Posts: 10
Joined: Sun Jul 29, 2018 11:58 pm
Location: Fife , Scotland .

Re: 750k wont pull at low revs

Post by jordihutch »

Hi , Thanks again for quick response . I am not an expert but I think all the carb parts have always been kept in the right "bundles" . I have only set them up to open etc at the same time statically ,as per the manual . then adjusted as per the book etc . It is almost to me like no amount of adjusting the carbs makes that much difference to the poor running , even after all the work / money that has went into it . cheers .
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BAZ
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Re: 750k wont pull at low revs

Post by BAZ »

You really have to get to basics to solve a problem take nothing for granted what was the compression readings and how was the suction test...
jordihutch
Posts: 10
Joined: Sun Jul 29, 2018 11:58 pm
Location: Fife , Scotland .

Re: 750k wont pull at low revs

Post by jordihutch »

Hi Baz , I am new to posting on here as well , may be replying to wrong high speed responses . I am sure we checked compression etc when it was rebuilt and I think the suction is ok too . Although I have done the carbs many times , it might be worth getting them checked / rebuilt by someone like yourself , I have seen the add on Ebay. Will check back on here tomorrow to see what others are saying . thanks for all the help so far , I really must get this up and running properly this spring . Cheers .
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