Author Topic: Newbie to Odyssey, carb issue PLEASE HELP  (Read 1883 times)

JohnW

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Newbie to Odyssey, carb issue PLEASE HELP
« on: July 15, 2010, 06:04:58 AM »
I am new to 2 strokes I must start off with? About 2 months ago I purchased a FL350 that needed a piston. I had head bored and an 81mm piston installed with proper clearance, exhaust bridge clearance, and vent holes drilled in piston. I am running 32:1 ratio with 93 octane fuel. The Odyssey will start on first or second pull every time and idles great. The problem is from zero throttle to about half throttle under load or in neutral the engine smokes excessively and boggs, but once you get past about half throttle it clears up it runs great until you return to idle. From half throttle to full throttle it runs awesome. It has a gravity fed system with new tank and no pump. It has a 142 main jet and I can?t remember, but I THINK a 42 low jet. I am not running the factory air box; I have a k&n set up on it.  Then needle is on the 3rd clip. We have tried moving the clip from top to bottom with only minimal changes, mostly in top end. About half way through our attempts yesterday when my friend moved the clip on the needle and reinstalled the slide apparently the clip came off and the needle sat in the carb and did not move with the throttle slide (we did not realize this until we took slide out after testing it) but the reason I say this is because with this error on our part it ran awesome on bottom end, no more excessive smoking, terrific throttle response, it was awesome, but had the occasional hiccup at full throttle. Needless to say we were shocked when we removed the slide and noticed the clip was off of the needle. We replaced the clip and right back to the same ole same ole, smoking and bogging. We started the air screw like the manual says 1.5 out and have tried each way with little or no change. CAN ANYONE OFFER ME ANY ADVICE?????? I have spent days on the various forums doing research, but this problem seems a little different than any others on here. And I am not sure if it is relevant but the ignition switch is not there (like that when I purchased it) the 350 has been wired where it is hot all the time, the kill switch works and when it is cut off we just leave it in the off position. Thank you all in advance for any help, and BTW, great forum, you guys seem very knowledgeable.

hoodlum

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Re: Newbie to Odyssey, carb issue PLEASE HELP
« Reply #1 on: July 15, 2010, 01:46:47 PM »
Quote from: "JohnW"
I am new to 2 strokes I must start off with? About 2 months ago I purchased a FL350 that needed a piston. I had head bored and an 81mm piston installed with proper clearance, exhaust bridge clearance, and vent holes drilled in piston. I am running 32:1 ratio with 93 octane fuel. The Odyssey will start on first or second pull every time and idles great. The problem is from zero throttle to about half throttle under load or in neutral the engine smokes excessively and boggs, but once you get past about half throttle it clears up it runs great until you return to idle. From half throttle to full throttle it runs awesome. It has a gravity fed system with new tank and no pump. It has a 142 main jet and I can?t remember, but I THINK a 42 low jet. I am not running the factory air box; I have a k&n set up on it.  Then needle is on the 3rd clip. We have tried moving the clip from top to bottom with only minimal changes, mostly in top end. About half way through our attempts yesterday when my friend moved the clip on the needle and reinstalled the slide apparently the clip came off and the needle sat in the carb and did not move with the throttle slide (we did not realize this until we took slide out after testing it) but the reason I say this is because with this error on our part it ran awesome on bottom end, no more excessive smoking, terrific throttle response, it was awesome, but had the occasional hiccup at full throttle. Needless to say we were shocked when we removed the slide and noticed the clip was off of the needle. We replaced the clip and right back to the same ole same ole, smoking and bogging. We started the air screw like the manual says 1.5 out and have tried each way with little or no change. CAN ANYONE OFFER ME ANY ADVICE?????? I have spent days on the various forums doing research, but this problem seems a little different than any others on here. And I am not sure if it is relevant but the ignition switch is not there (like that when I purchased it) the 350 has been wired where it is hot all the time, the kill switch works and when it is cut off we just leave it in the off position. Thank you all in advance for any help, and BTW, great forum, you guys seem very knowledgeable.



First,is your needle worn or damaged? Look for signs of excessive wear around the end of the needle,or see if the tip has been broken off,or even if the needle is bent.....
Second,you mentioned the fact it was gravity fed...Chances are that whoever done the conversion didn't change out the valve in the carb....Not real sure on the specifics,but going from pump to gravity requires a different needle valve in the carb...You can find more info on that here as well....
Third,check to make sure your exhaust is not plugged up by a dobbers nest,dead mouse,etc...This can cause a bogging condition as well....
I might carefully try to put the needle in there again without a clip and just try it to make sure that's what made the difference,or wether it was something else,and it happened to fix itself for a short time...Notice I said carefully,becaust it could lean your engine out completely and sieze it....
Hoodlum

hoodlum

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Newbie to Odyssey, carb issue PLEASE HELP
« Reply #2 on: July 15, 2010, 01:56:04 PM »
Here is a previous post that tells more about the gravity feed problems...


THIS IS THE 2nd MOST IMPORTANT THING TO DO ON A ODYSSEY!!!
This message will tell you how to Plumb fuel lines on ODY's using 3 different combinations, the first is for a stock Keihen on the odysseys or pilots and or a Mikuni usiing 2.5 Float valves. The third is how to plumb the fuel lines when you are using a Mikuni with a 1.5 float valve.

On all 250, 350, & 400 Pilots, ALWAYS MAKE SURE YOUR GAS LINES ARE NO OLDER THAN 5 YEARS OLD AND THE FUEL PUMPS EVERY 10 YEARS.

On the pick up or negative pressure side of the fuel line system, you have to use only the FIBER REINFORCED BLK FUEL LINE, use 1/4" ON GAS LINES & 3/16 ON VACUUM LINE. On the pressure side of the system, from the fuel pump on out to the carb (and if you have the T from there on back to the tank) you can use clear blue fuel line. NEVER USE rubber vacuum lines or the gray fuel lines with out fiber reinforcement.


This picture has a replacement T with a metering jet in the T where the line goes back to the fuel tank. You can also add a check valve in the line that goes from the T on back to the tank, this will keep the fuel pump from loosing prime.



The side of the fuel line system that is on the negative or vacuum, which is from the petcock to the fuel pump needs to be a 1/4" inch fiber reinforced fuel line.
The same goes for the vacuum line that make the fuel pump operate, only that this line should be a 3/16" inch fiber reinforced fuel line. This is actually the most important hose to replace as soon as possible!
Now on the positive side pressure, that is from the fuel pump on out you can use the clear or blue clear lines that have no reinforcements.

* HOW TO CHECK THE HONDA PRESSURE T THAT DIVERTS GAS TO THE TANK
To check the HONDA T, hold it to your mouth with the pressure valve pointed away. Put your thumb on the bottom of the T and blow. IF it blows easy but you can not suck in, just like a check valve ITS BROKEN!! When you blow it should not allow you too until you build allot of pressure up. Then it will continue to blow with heavy resistance and lock up before you can come near running out of breath, that is a good working T.

THIS APPLY ON ALL THREE 250 - 350 - 400'S
USING THE ALUM. TANK W/ KEIHEN CARBS
When you are using the stock Keihen Carb or any Keihen Carb you will need to mount a chromed valve stem into the neck of the alum. tank. After you mount valve stem remove the center core and then you can hook the 1/4" return fuel line back into it.

ADD THE CHECK VALVE IN THE LINE GOING FROM THE RETURN T TO THE TANK !! This will keep the fuel pump from loosing prime.

THE Basic system is the same as above, you just have to remount your fuel pump anywhere you like. The fuel pump can be upside down to right side up, it doesn't matter. Just remember to use a 3/16 fiber reinforced line to run it.

NOW I HIGHLY SUGGEST THAT YOU NEVER USE THE GRAVITY FEED SYSTEM!!!
When your using the stock carb or any or all Keihen carbs they all have the seat of the float valve (needle & seat) pressed into the body of the carb. Kehien uses a 2.5 float valve that is in the middle of no where. It is to big for you to be able to run the fuel line direct, if you do it will flood the carb. 2.5 is to small to gravity feed
To gravity feed HAVE TO HAVE A 3.5 or a 4.0, with the 2.5 you will only lean your fuel and damage your top end when you make more than a 200 yard dash or further at full throttle. That is because a 2.5 is the same as having a 1/32" hole, so it will not keep up with over 1/2 throttle.

The problem is that even when you use the proper sizes, 3.5 or a 4.0 float valve when using the Mikuni carb is that after you burn off the first gallon of gas it will begin to slosh side to side. That will only leave aprox. 2 inch's of gas in the center over the petcock. Now 2" is not enough weight to push the gas through a fuel filter and keep up with your carb when over half throttle or you will run your fuel bowl dry, even if it is for only a few seconds, it only takes 20 seconds to damage the rings and soon after you do it over and over you will more likely burn another piston out.
.
PLUMBING THE MIKUINI CARBS

IF YOU REPLACE YOUR CARB USING MIKUNI CARBS WITH A 1.5 OR THE 1.8 FLOAT VALVES
USING THE MIKUNI CARBURETORS IS THE BEST FIX that you can use to replace the stock Keihen or any Keihen carb. In the Mikuni TM carbs you can change out the float valves (needle & seat) to a 1.5 and that way you can run the fuel line directly from pump to carb WITH NO T's.

Using the Mikuni carb you plumb your carb this way:

We use the 3/16" fiber reinforced line for a vacuum line. The line from the petcock to the filter and from the filter on to the pump is a 1/4" fiber reinforced fuel line. From the fuel pump on to the carb you can use the clear or the blue clear fuel line.
ALWAYS use the stainless steel radiator style hose clamps, not spring or wire clamps, on all the fuel line ends.

WHAT TO DO WITH WHERE THE FUEL LINE RETUNED INTO THE TANK
Where your return line use to return on the top of the tank will not be needed anymore now. What most people do is to install a new 1/4" fiber reinforced fuel line to the old return line inlet, that will be used now as a vent line.
To do that you will twist the 1/4 inch fuel line into a tight 3" circle and zip tie it to the top of the tank, then let the rest of the line fall down to the bottom of the tank where you will zip tie it again. Most guys will put a old fuel filter on the end of that new breather line to keep the dust out.

Now on all carbs I really suggest that you use the throttle cable to adjust your idle. Adjust the cable on top of the carb up as far as possible. Then finish that adjustment on the steering wheel that way as the seasons change you can easily change the idle.
 

Hope this helps
Hoodlum

JohnW

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Newbie to Odyssey, carb issue PLEASE HELP
« Reply #3 on: July 15, 2010, 04:39:10 PM »
Ok, I did a leak down test today, I pumped it to 7psi and 25 mins later it was at 5 psi, is that ok? The xhaust is not stopped up at all. the stock carb is on it with stock needle and everything, it seems to be fine, nothing visible wrong with it. it has a 42 slow jet and 145 high speed. It is running to rich, fouled out plug today after about only 10 mins of riding. also did compression check it was 130 psi hot. I am lost here, i talked to randy at odyssey salve for  a ahile today and he gave me some great tips, but not much helped today. I know I am going to have to put a pump on it, but without pump it will run lean on top end, it is running way rich on bottom. So i feel like the pump is not the cause of this problem. I have ordered a pump. I have read on some of the forums where witing problems have caused similar things, any ideas on that or anything else? i will try tomorrow to run without clip on needle to see if it has the same effect as it did yesterday. Thanks for the response.

hoodlum

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« Reply #4 on: July 15, 2010, 08:14:45 PM »
Quote from: "JohnW"
Ok, I did a leak down test today, I pumped it to 7psi and 25 mins later it was at 5 psi, is that ok? The xhaust is not stopped up at all. the stock carb is on it with stock needle and everything, it seems to be fine, nothing visible wrong with it. it has a 42 slow jet and 145 high speed. It is running to rich, fouled out plug today after about only 10 mins of riding. also did compression check it was 130 psi hot. I am lost here, i talked to randy at odyssey salve for  a ahile today and he gave me some great tips, but not much helped today. I know I am going to have to put a pump on it, but without pump it will run lean on top end, it is running way rich on bottom. So i feel like the pump is not the cause of this problem. I have ordered a pump. I have read on some of the forums where witing problems have caused similar things, any ideas on that or anything else? i will try tomorrow to run without clip on needle to see if it has the same effect as it did yesterday. Thanks for the response.



Please read the previous post again....When useing the gravity feed,the 2.5 needle valve will flood the engine on the bottom end,but not be able to keep up on long wide open runs....You just haven't been on a long enough run to empty the carb bowl yet...This is what your engine is basicly doing...The stock carb is set up for a pump feed which gives more fuel pressure as the rpm's increase...The gravity system gives you the same amount of pressure all the time,which is too much at low end and not enough on top end for the stock carb......I would suggest dumping the gravity feed,read the previous post again on how to plumb in the tank you currently have to allow use of a pump...They are much cheaper than pistons,cylinders,and bearings....
As for the wiring,I am sure you are referring to the reverse rev limiter,which restricts the rpm's when going in reverse...If the wiring is grounded out,it will cause it to operate in forward as well,but if that was the problem,it would never clean out or rev up...It would constantly sputter around at about 10mph and never go any faster...
I am almost totally convinced that the gravity feed set up is your problem......
Hoodlum

JohnW

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« Reply #5 on: July 15, 2010, 08:23:27 PM »
Ok, makes sense now.. thanks

Adnoh

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« Reply #6 on: July 17, 2010, 08:07:10 AM »
You can test the gravity tank theory by removing the majority of the fuel and that will reduce the weight of the fuel ( presuure) on the float neddle. Since the weight of the fuel may be causeing the pressure problem. Drain the tank into a good can and then put back  enough to fill the line and a little extra and test. Re set the carb to a good setting  for the test. I'm not saying go take it out on a long test drive just enouhg to clean it out and see if it loads back up.

If you think about it( the valve nedddle) and the amount of pressure on it  that is created by the fuel in the tank ( over head). If the pressure that it is entended to stop the flow ( fuel in carb raising the float and shutting the valve)is less, it a lot harder to stop the flow.  Just ask BP about that one. It not that it can not stop flow it just not soon enough and effecting the amout in the bowl and flodding the engine.

At WOT the fuel that is flowing under a higher pressure is being consumed at a quicker rate than at idol and off idol.  Not chop the throttle and the valve needs to stop the flow under the new pressue rate ( the weight of fuel in motion). The float can not shut it off soon enough and causes the bowl to over fill and load the engine up which requires some WOT to clean it back out.

A good way to look at is a garden hose and the hose bib. Turn the hose on a little and put your thumb over it and see how far it sprays. Now turn it all the way up and repaet. It sprayes a lot farture based on the pressure of the flow. Now try to stop it with your thumb. You can slow it down but cant stop it from spraying a little. Not how much more hand pressure did it take. See the water tower is like the over head fuel tank. just a hole lot more extreme.

Now thats that out there ths is why they put pressure requlators on the water systems or the toilet runs all night and the float in the tank can not stop it due to it can not create enough counter pressure to close off the valve.  The staic prssure is at the point to where once it starts flowing it take a lot more pressure to stop it based off of weight/volume.

If the drained tank test works then there your proof. If the engine cleans out and run then just fill it back up and see if the problem comes back.

What about a pressure regulator in line, as an option if all else fails. If indeed a pressure problem.

JohnW

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« Reply #7 on: July 22, 2010, 05:12:42 AM »
Ok, I put fuel pump on, t with return to tank on yesterday and still same problem. I rechecked compression with a new gauge and i have 140psi. cranks first or second pull ever time but boggs from idle to half throttle. guy i got odyssey from had a 7 plug init, i went to an 8. it is running very rich. exhaust is not stopped up leakdown test was fine. ive cut a half inch off of plug wire, it has a 45 pilot jet in it and i set float level to 16mm. so....... any ideas? like i said before the guy i got it from eliminated the ignition switch and has it straight wired, I am going to take my manual tonight and make sure everything is hooked up like it should be but does anyone have any other ideas?

thanks for any sugestions. and i have bypassed the shift switch also

hoodlum

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« Reply #8 on: July 22, 2010, 06:18:54 AM »
Quote from: "JohnW"
Ok, I put fuel pump on, t with return to tank on yesterday and still same problem. I rechecked compression with a new gauge and i have 140psi. cranks first or second pull ever time but boggs from idle to half throttle. guy i got odyssey from had a 7 plug init, i went to an 8. it is running very rich. exhaust is not stopped up leakdown test was fine. ive cut a half inch off of plug wire, it has a 45 pilot jet in it and i set float level to 16mm. so....... any ideas? like i said before the guy i got it from eliminated the ignition switch and has it straight wired, I am going to take my manual tonight and make sure everything is hooked up like it should be but does anyone have any other ideas?

thanks for any sugestions. and i have bypassed the shift switch also


Did you plumb the tank correctly? If you didn't,you still have a gravity feed system...Can you fill the tank,pull the fuel line off the pump without dumping a bunch of fuel from the tank? Your fuel line needs to make a loop above the tank so that the pump is having to suck the fuel from the tank...What kind of T did you use? Does it have a check valve in it? Some pics of your fuel tank/pump setup would be helpful....

JohnW

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« Reply #9 on: July 22, 2010, 06:50:11 AM »
I used the t from randy at odyssey salvage. it has a check valve in it to return fuel to tank. And no, I have the line going straight down from the tank to the pump. I will try the loop when I get home from work today.