GPZ1100 Unitrak - cold start issues

[bigrocketrider]

Its winter so I am back to the GPZ1100 and really feel as though progress is being made. This is a great looking bike but is a real pig to run from cold. Once up to temperature she ticks over lovely at 1100-1200rpm and revs freely - its actually really nice to ride. But from cold - what a bastard!! I have now cleaned and set the TPS (this must be right otherwise it wouldn't run when warm), cleaned the temp sensor, new air filter, cleaned fuel injectors, fuel pressure and fuel return valve in tank and I have no ecu flashing at me. From cold its as if she needs choke and the fast idle has little affect. That said, the fast idlel must be fine as it works ok when the bike is warm taking revs up to approx 4000rpm. Plugs indicate she is still running rich. I want this on the road from next year but really couldn't put up with it taking so long to warm up - I ride my bikes. I am clearly missing something really simple here so any further advice most welcome.

[pluto]

Fast idle lever is just that, it operates a cam that opens the throttle a bit, doesnt richen the mixture for starting though. That's taken care of by the engine temp sensor and possibly if its really cold outside by the air temp sensor in the airbox. If it wont start and it is DFI related then clean all the terminals again and try a known to be working engine temp sensor, as it runs off 0 - 5 volts a little corrosion causes alot of probs. Have you done a compression check or checked the engine will start from cold with a good set of carbs on? As its appearing rich on the plugs it could well mean that its mechanical (worn bores,leaking valves) or electical (coils plugs etc) rather than DFI related.

[bigrocketrider]

Cheers Pluto. Understand how the fast idle works but it just doesn't increase the revs when first started - only increases revs when its warmed up. The bike starts first time every time - it just flutters about at 1500rpm and takes an eternity to warm up. I've set up and balanced the throttle bodies as well and new coils in place and it runs real sweet when warm. Think I will take the engine temp off my Z1000H and see if that makes any difference although the one on the GPZ looks to be in pretty good shape. Compression check next after that I guess.

[PAULJAC47]

Have you done the shims? tight shims can cause cold start issues..Stick a rolled up rag over air intake on filter and see if that helps,i help id the prob,dont think plug colour is as much of an indicator these days with our crappy fuel.May be worth putting a Gunson in to see if you are enriching/choking the engine from cold..Good luck..

[z1bman]

check for air leaks especially the breather pipe from the engine to airbox

[bigrocketrider]

cheers for your guidance guys. I will try both of these hopefully over the weekend.

[bigrocketrider]

All sorted. TPS at fault in the end. Had two so gave them both a thoroughly good clean with electrical cleaner and bike is now starting and running fine. Thanks for the advice guys - got there in the end.