Why is my bike so hard to start when its cold?

First my bike had a hard time starting when it got hot, Now it has a hard time starting when its cold. Sombody please tell me how to make it just right!!!!. My battery will almost die ,so i have to hook up the charger, then it will finally start. :D:)

I am sure that someone here will steer you in the right direction, but lets start with some of the basics.

What bike do you have

What modification have been done (Diffent map for example)

What spark plug, how old.

What service bulletins have been done

etc. :)


The IACV system has proven itself very unreliable. This would be my first guess. If your stuck closed, or too far open, it will have a definate effect. Mine had the stuck open/high idle symptom, but I believe HRs was very hard to start like yours. Just about everyone here has gone through an IACV stepper. This should be at the top of the list for redesign/new part. I now have a manual replacement on my bike that you use like a choke lever on any other bike.

Start with the spark plug. Is it burning clean? The Dales tend to come fat from the factory and need to be leaned out. Secondly if you have been running rich and have not cleaned your spark arrestor that will compound the problem. The mesh is real fine and plugs easily. Fat fuel plus a plugged spark arrestor will lead to all kinds of performance problems. I would start with the plug and spark arrestor.


Mine is the same way when cold. I was up in the mountains a few weeks ago and it was about 30º in the morning. It took 8-10 tries before starting. Mine is running fine and no plugged exhaust. Starts on the first or secong try when average temperatures exist. Although, it did come up to a temperature, much quicker now than it did when running fat when new, and able to rev and ride in less than 3-4 minutes.

My dealer said he had this trouble and what worked for him is to hit the button to turn it on, hit it one more time to prime it, then the third time, hit the button just before the pump shuts off and it fires up. Haven't been able to tyr this on mine since it warmed up the last couple weeks. But tomorrow night should be pretty cold, I may try it on Friday and see what happens. This is similar to what I found is that it needs more priming to get it started when fairly cold. Just need to get the technique worked out, possibly change the prime specs in the map.


Yes, multiple hits on the button and it starts first try. Usually two, but when cold out three. I was assuming he checked the obvious.

The manual IACV I installed works great. Flip it to open, and the bike starts normally. Unlike the stepper driven metering valve, as the bike warms the idle will now gradually rise. When it gets noticably high (a few minutes), flip the valve off and your good to go. Very reliable and totally reversable if/when an improved stepper is available. The automatic system is more important on a road bike, where cold rideability is more of a concern. A race bike should always be warmed up anyway. FYI, I have actually started the bike with the valve off quite eaisly, even at about 40 deg. It idles very rough until warm though.

Another benefit is that with the stepper gone, I can now fit a 4" fan, where a 3" was tight before.

Glen do you have a write up for your stepper replacement?


...pics would be awsome.

I think I have that problem....what he said.


While I was recovering from my wrist injury, I did many small mods that together added up to big results. I planned to do a write up when I was satisfied. I have some photos, but none of the manual valve yet. I have to borrow a digital camera. In short, the system is basically a .1" thick aluminum plate that replaces the IACV housing, with two 1/8" barb fittings, one for each port above and below the throttle plate. These are connected with automotive vacuum line to a pneumatic toggle valve mounted to a 4" bracket that bolts across the top louver mounts of the radiator. The valve looks just like a 1/2" panel mount toggle switch, and is available from industrial suppliers like McMaster Carr. You can make the plate by tracing the IACV housing with a scribe, and some careful hacksaw and file work. Seal up and tie back the stepper connector and thats it, it doesn't need the stepper to run, although it will show up as a fault on the D&M tool.

I have a couple of funny questions re: stepper. You said you were able to easily start at OAT's as low as 40 F? Do you think I could get away with not having it at all in So Cal? And, how much weight do you think it would save removing it?


Joe :)

Try it, its easy. Just disconnect the motor when the bike is warm to hold the IACV closed. The bike will start but run very rough with a low idle from being too rich (no bleed air), until it starts to warm up. The stepper only weighs a few ounces, but more important to me is I don't have to worry about it totally failing (open) on a 50 mile ride, and it takes up valuable airflow space close behind the radiator. Last ride I had to stop and restart the bike over 10 times to clear a high idle from the IACV not closing properly.

I have a few friends with Suzuki Hyabusas, a modern fuel injected streetbike. I was surprised to see that the bike had a manual choke. I don't understand why Cannondale added complexity as well as something else to go wrong when they could have just kept it simple with a manual bypass on the throttle body.

Exactly. I'd bet the origins were from the Triumph road bikes, where the same system is used.

Hey GP, just be glad they didn't have Lucas do the wiring and electronics!!

You got that right. My buddy from high school had an old Tiger, what an electrical disaster. A ball of wires crammed into a steel headlight shell with loose insulators!

Hey GP, sounds like you know what to do with this problem. My bike is an E with x mapping and a cut down pipe. I've had my rep change the mapping and the settings, I'm not sure what they are though! I've replaced my stepper twice!!! And both times it would just stick open, the nylon threads on the inside strip out. I would like to have the comfort of knowing my bike is not going to leave me stuck some were, but until I can get this stepper thing fixed Im not going to be happy!!!

I hear you. Do the mod, problem solved. I beleive the stepper failures are aggrevated by heat, from both internal "holding current" and external heat from the rad. I'm an EE with experience using steppers and linear actuators(a stepper motor with a lead screw like the IACV) in designs, and have seen similar failures with small devices at high loads and temp extremes. I would like to see the number of failures in the quads vs. the bikes, as the rad is much further away in the quads. BTW, mapping has nothing to do with the IACV function, its driven by coolant temp.

I have to agree with GP on the issue of heat. The stepper is located close to the radiator. Add in some of the overheating problems at slow speed and you have less than ideal conditions for long life.

I recently dropped my engine for service and some mods. I noticed a light build up of carbon on the throttle body. I suspect that if the engine is running rich, that the carbon build up is more prevalent. It is possible that carbon may be finding its way into the stepper mechanism and causing it to bind.

If you take into consideration a rich mixture and the overheating I would think that you have a receipt for a short life on the stepper.

Another thought to consider is that a lot of guys had switched to the 8 plug to compensate for the fat mix. This may actually compound the problem. The 8 will cause the engine to run hotter, bad. Also the I suspect that the carbon build up may be greater. Both conditions leading to potential stepper problems.

What can you do? In warmer riding conditions use the 9 plug (note with colder riding weather approaching, temps below 60F, I would use the 8). Spend the time to get the mixture right by reducing the injector offset and run one of the enhanced coolants in the radiator i.e. Engine Ice, Water wetter etc.

I can say that I have run 9 plug, have not overheated my engine and have the mixture dialed in and have not had any problems with the stepper (knock on wood). My experience may not be conclusive but it does make sense. Heat and crud are an engines worst enemies anything you can do to minimize both will only enhance engine reliability.

BTW just sent my engine to South Bay for their Stage 1 engine mods which includes a Big Gun Exhaust. It should give the engine solid mid range pull and allow for easier short shifting. I should have everything back together in about two weeks. I’ll write something up after a ride or two.


Big Gun exhaust? I e-mailed them last week and they said they weren't producing them yet.


I indeed did find some carbon in the IACV housing. I suspected this was from the popping and stalling problems I had from the shorted O2 sensor wires. Also, the pressure pulse from a back fire would not do it any good either. As part of my mods, I insulated everything behind the rad. The insulation and adhesive has held up fine on the air box and all components but the stepper, where the adhesive has blistered away and the insulation fallen off. This tells me that the stepper generates a significant amount of heat by itself.

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