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Kz750ish carb advice
- jeffo
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1981 KZ650H1 CSR
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- Tyrell Corp
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Think of the 'signal' a carb gets when the throttle is part opened...the difference is like like sucking a drink through a drinking straw or a hosepipe. Instant throttle response and pick up might be compromised if you over carb it.
The late GPz750 and 1100 both share the same 34mm carbs...you need to be at quite a high state of tune before your carb size is a limiting factor in my opinion.
1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces
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- jeffo
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Tyrell Corp wrote: I doubt if you need bigger carbs on what is a mild state of tune. you could lose a lot more bottom end than you gain on the top.
Think of the 'signal' a carb gets when the throttle is part opened...the difference is like like sucking a drink through a drinking straw or a hosepipe. Instant throttle response and pick up might be compromised if you over carb it.
The late GPz750 and 1100 both share the same 34mm carbs...you need to be at quite a high state of tune before your carb size is a limiting factor in my opinion.
Thanks. I will give it a go with what I have and go from there.
1981 KZ650H1 CSR
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- tylerstedham
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- jeffo
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1981 KZ650H1 CSR
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- tylerstedham
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- jeffo
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1981 KZ650H1 CSR
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- redhawk4
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Regarding jetting, IMO many get a little carried away, you need to bare in mind that a carb does have some ability to allow for extra cc's in it's basic function. If you pull more air through a carb because you have extra CC's, it also draw in more fuel with that air. If the engine is remaining stock other than the overbore and was jetted correctly before hand then the changes required will be minimal.
My recently acquired KZ1000A2 has the 1075 kit and the PO had, IMO, got carried away with the jetting thinking the extra capacity was a big deal, as a result it didn't run well. returning closer to stock has made a huge difference to starting and idling. Being at altitude seems to have a big effect on idling and slow running, I think the thin air is more noticeable a low rpms and so it's easy to go too big on pilot jets. I've found keeping the pilot jet relatively small and running a bigger main jet so you don't get the engine too hot on the top end has worked well on a number of machine's carbs I've modified. I have a Honda XR650L, they come super lean from the factory, but with the altitude I could only go up one size on the pilot jet, I jumped two sizes initially because I had some other mods too, but it would bog when accelerating, two sizes more on the main jet worked fine.
Personally if it was me I'd get it running with stock jets first to see how far out that was before jumping to any conclusions. I'm not personally a fan of the dyno jet kits, I like to just buy the individual jets, based on how running with stock jets was working and how they feel. The dyno jet kit can throw in too many variables at once, if you change everything in one hit and don't get the result you hoped for, it's difficult to know where you went wrong.
1978 KZ1000A2 Wiseco 1075 kit
1977 KZ650B1
1973 Triumph Tiger TR7V
1968 BSA Victor Special 441
2015 Triumph Thunderbird LT
1980 Suzuki SP400
Old enough to know better, still too young to care
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- SWest
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Steve
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- redhawk4
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1978 KZ1000A2 Wiseco 1075 kit
1977 KZ650B1
1973 Triumph Tiger TR7V
1968 BSA Victor Special 441
2015 Triumph Thunderbird LT
1980 Suzuki SP400
Old enough to know better, still too young to care
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