Has anyone put a manual choke on a carbed 650 Prowler. I have one with big bore kit 700cc plus head work from Speedwerx and exhaust. This unit will start when cold and when hot but will not start when warm like sitting for 30 mins to 1 hour after a run without cracking the air box lid. I think the ele choke is open and making it to rich to start the warm motor. Any ideas??
Manual choke on a Prowler
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Welcome to the site racebum.
You have probably already thought of some of this.I will post it just in case you have not.In order to get a rich mixture to light you have to introduce enough air for it to com bust.With a cv carb this is a little more difficult but can be done.If you hold it throttle wide open and it will start then you know you are on the right track as far as it being to rich.If it is too rich and you hold it wide open it will take some cranking to get some of the fuel evaporated and enough air in it to light it off.In my opinion the next time you shut it off and you go to restart it put the peddle on the floor and start cranking.It should take about 4-8 seconds for it to light off.Remember though it is a cv carb so there are two butter flys in the carb.One that is connected to your foot and one that is opened when the vacuum from the motor says ok I can handle it.With that size motor I would at lest trim the spring in the diaphragm of the carb to get some better response and better low and mid power.Or put a bigger carb on it.The stock 650 carb is marginal at best.So in my opinion you are leaving a lot on the table with it.As far as the choke coming on when it is hot you could be right.What i will say is that if you have changed the cam to a bigger one the fuel it needs at starting and idle is probably less than a stock one.I can get into that if you need me to.
You have probably already thought of some of this.I will post it just in case you have not.In order to get a rich mixture to light you have to introduce enough air for it to com bust.With a cv carb this is a little more difficult but can be done.If you hold it throttle wide open and it will start then you know you are on the right track as far as it being to rich.If it is too rich and you hold it wide open it will take some cranking to get some of the fuel evaporated and enough air in it to light it off.In my opinion the next time you shut it off and you go to restart it put the peddle on the floor and start cranking.It should take about 4-8 seconds for it to light off.Remember though it is a cv carb so there are two butter flys in the carb.One that is connected to your foot and one that is opened when the vacuum from the motor says ok I can handle it.With that size motor I would at lest trim the spring in the diaphragm of the carb to get some better response and better low and mid power.Or put a bigger carb on it.The stock 650 carb is marginal at best.So in my opinion you are leaving a lot on the table with it.As far as the choke coming on when it is hot you could be right.What i will say is that if you have changed the cam to a bigger one the fuel it needs at starting and idle is probably less than a stock one.I can get into that if you need me to.
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Also to answer your question I have run a mikuni tm 42 on my prowler 2 and a half years ago.Worked pretty good.I like the accelerator pump part of it.It did run pretty good.Cost me some coin though buying all the jets and needles to get the thing tuned.
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Race Bum,
How do you like the big bore kit with the headwork and exhaust from Speedwerx?
I know alot of people purchased the Huntworks carb and liked it? Is that the same one you are talking about Sandchris?
Sandchris yes could you tell me why less fuel with cams. Mustanggeek If you do the big bore you need to do the whole thing CDI exhaust etc. The one we are working on does not have all the goodies and I think that is why we are having problems. Sandchris it does have the bigger cam and uses the stock intake.
No I dont think so. It just seems like the choke is on when it is warm and the motor does not need the richer mixture to start. The prowler fired up this morn no problem, but if you ride it for 20 or so mins then shut it off then come back 20 mins later it wont start. Yesteday I ran the prowler and went back out in thirty mins and turned the key on for 2 mins and tried to start the unit same thing. The next time I left the key on for 5 mins and it did at least try to start. That tells me that the choke is cooling of faster than the motor. I need to take the choke out and power it up and see how long it takes for the choke to reach its full length. Man I am glad we are talking about a ele choke and not something else!!
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Generally when you install a performance cam what has been changed is the amount of valve lift.Most of the time they have ground the cam for a higher lift and maybe some more duration.They might have changed the overlap too.For now lets focus on the lift.The restriction in the intake trac is the slide on the carb and the intake valve or valves.When the engine is idleing it has a certain amount of vacume signal that the carb is using to meter fuel.If you change that vacume signal the carb is gonna do different things too.Another thing that is important is atomazation.The better atomazation you have the better idle quality and overall peak horse power and gas mileage you will have.And as you probably already know atomazation is important because the more oxygen molecules you can get around or to cover the gas molecules with the better the fuel will burn.So with that being said if you have a intake valve that is a restriction at say a certain lift and you install a cam.And the valve now opens farther.You have changed the vacume signal that the idle circut of the carb sees.With the valve opening farther and less vacume the fuel is being atomamized less so even though there is enough air there to support combustion the fuel is not being coated with oxygen as well as with more vacume.Not sure if this is a huge problem with your motor work but pretty sure some of this could be going on.Not a deal breaker but you could be getting a rich smell while idling.Could be a little harder to start too after it is warm.
You are correct on the smell at idle. This unit will not idle at all until it is ran for at least 5 mins. If you start it and walk away it will die. John at Speedwerx said to double check the timing because the lines on the cam dont line up like they should (straight across). So we went one tooth the other direction and the lines where just oppsite of the way they were and man it made a difference. So I was one tooth off on timing. It still does not want to idle well but I can live with that. That is what a BIG BORE does.
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