Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

Tecumseh OHH65 on Yerf-Dog


BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

08-12-10, 12:43 PM   #1  
Tecumseh OHH65 on Yerf-Dog

This fun kart has the mentioned Tec engine, 6.5HP OHV. Engine bogged under heavy load. Up hill or in hard corners...
Overhauled carb with new float valve kit. Valve clearances check ok, .04 intake .05 exhaust...new plug, changed the oil, not over full....found the original air filter looked clean but later noticed it smelled of gas so I replaced it.

Problem is it will bog under load with the air filter installed, but remove it, and it does not.
The new airfilter now smells of gas also...that is when I changed and refilled the oil. It seemed awful thin but did not smell of gas, and on this engine, the intake runs uphill so I don't think the old seat leaking mixed in the oil...still I changed it and same issue.
I am thinking I should try another new airfilter but can not imagine what else might be choking it off under load and causing the airfilter to get gased.
Does fine with just the pre-filter as well....

 
Sponsored Links
jl66redcpe's Avatar
Member

Join Date: Nov 2006
Posts: 367
NJ

08-12-10, 01:11 PM   #2  
I just finished a Yerf-Dog 3200 with the same motor. It would not idle properly and surged at idle. It also had the gas stained filter. In fact gas was slightly seeping out the air filter housing behind the filter. I had to change the float, needle and seat and that solved the problem.

 
31YTech's Avatar
Member

Join Date: Feb 2008
Posts: 1,263
FL

08-12-10, 06:32 PM   #3  
BFHFixit,


Take a look at the inside of the air filter cover, They have a small red plastic flap inside. Make sure it hasn't been moved to the winter run position which reduces air intake.

Since this engine is tilted, When you installed the new float valve was the float adjusted slightly above level when the carb is held up side down ?

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

08-12-10, 09:31 PM   #4  
I did just replace the needle valve and seat prior to replacing the air filter. Left the cover off and no signs of fuel leaking.

31YTech,
I did discover that flap and it is/was in the summer position allowing the most air in.
As for the float, when I had it on the bench the float was level with the carb. I actually tweaked it a hair due to initially thinking it might be starving since the complaint was mainly when on a hill. So the fuel level is a bit higher now...maybe the wrong way?

 
31YTech's Avatar
Member

Join Date: Feb 2008
Posts: 1,263
FL

08-13-10, 04:06 AM   #5  
Posted By: BFHFixit maybe the wrong way?

Well, I tend to think so. Tweak it back up (holding up side down) to about 1/8" above level and give it another try.

I found years ago on these carbs with the non serviceable check valve, It's better/easier to replace them over trying to rebuild. Labor plus parts is about the same price as a new carb that you know will function properly....

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

08-13-10, 09:15 AM   #6  
I will give that a shot...
Where is this check valve? Welch plug or...?
The owner claims it has less than 10 hours on it, although the seat was quite crumbly so it has no doubt set for some time with fuel in it which.... and it looks like the only logical/safe place for a shutoff valve would be a tank mounted one.

Thanks for the reply.

 
31YTech's Avatar
Member

Join Date: Feb 2008
Posts: 1,263
FL

08-13-10, 06:06 PM   #7  
Haha, I can't guess the times I've heard "but it only has X hours on it" and it looking like heck.


This isn't the exact carb your working on but most all Tecumseh carbs have this sealed port area (HERE), There's a micro bb inside this port that gets stuck;





I rebuilt one years ago off a go cart and couldn't get it to run right to save my life, I installed a new one to get the job gone. I then stripped the old one back down and threw it into my 5 gal bucket of carb cleaner for a month.....Yes a month..... Put it back together then tried it on the next engine that came in, Dang thing still wouldn't function properly.

Not going to be beat I stripped it back down and attempted to drill the steel plug out of the end, Well.....It's hardened steel. Finally after admitting defeat I took my 3" cut-off tool to that area and cut it open, It is a small port inside but there just isn't any reasonable way to get to it for cleaning without destruction of the carb......




As for a fuel cut-off valve, The only place for one would be between the tank and where the hose goes behind the flywheel backing plate. But there isn't much hose length there for a in-line style.

 
31YTech's Avatar
Member

Join Date: Feb 2008
Posts: 1,263
FL

08-13-10, 06:11 PM   #8  
OOOPS.....Double post..... :repostit:

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

08-13-10, 08:59 PM   #9  
Too cool! Glad I asked despite my reluctance
I have wondered about that lil buggar for years now.
Agreed on the hours statement indeed!
Actually I think this is the same carb that is on my dang craftsman wheeled string trimmer and any eager 1 or any of many Tecumseh....kit gaskets and linkage is all the same...one thing I did notice was on the hinge pin for the float there is a spring like a return or sumin like for the float...goes between the hinge points on the carb...maybe it is supposed to hold the float down? I don't recall how I installed it as pressure on holding it closed or open...??? Regardless I don't think there is enough pressure from that wimpy spring to overcome hydraulic of even gravity.

Yep on the fuel valve too. If it were mine I might put an inline just under the tank, but it is pretty close to the cylinder to even use IMO for the unknowing. My fear would be someone turning off the valve after just running the kart and get a blister or sumin

As always,
Thanks much for sharing.

 
31YTech's Avatar
Member

Join Date: Feb 2008
Posts: 1,263
FL

08-14-10, 06:31 AM   #10  
Posted By: BFHFixit Glad I asked despite my reluctance
Reluctance to ask questions can lead to fewer answers.....

maybe it is supposed to hold the float down? I don't recall how I installed it as pressure on holding it closed or open...???

It's to help hold the float closed where there's more than normal vibration/bouncing around of the carb/unit.





Good Luck

Cya.....

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

08-22-10, 08:44 PM   #11  
Finally got my head out the closet flange long enough to adjust the float on this and then try it out again...same symptoms...

Guess I will try and resource a new carb.

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

08-30-10, 01:06 PM   #12  
Not to discount your input 31Y but I have done some more research on this and it seems to be a common problem in this application of this engine.
What I have done is taken one of the old paper element airfilter, peeled the paper off and used the seal and screen, then place the pre-filter on the carb side of it. With this config I can push the lil kart to the limit with little if any bog even in off kilter uphill situations. Note this limit does exceed how the Yerf-dog manual claims it should be used, most likely safety related...however...still trying to serve the customer.

I pulled the carb again and rechecked the spring,which btw, I cannot find a part# on any IPL for.... this must have been a managerial fix or sumin Beer 4U2

I was going to try changing the air filter housing to one that takes the barrel type filter....the screws for the housing on the kart are being particularly stubborn and will need drilling to remove...like wise on the housing I was going to try, the screws are not volunteering to come out...and it is a working unit so, I am reluctant to try it without access to another housing.
I informed the customer of the limitations Yerfdog mentions, and he understands. He is coming by tomorrow to look at the options I have for now....
Just not sure a new carb is gonna do what he wants it to do since it might be more of an application error than anything...might be time to start looking at mods if he wants more than its meant to do...?


Last edited by BFHFixit; 08-30-10 at 01:30 PM.
 
31YTech's Avatar
Member

Join Date: Feb 2008
Posts: 1,263
FL

08-30-10, 05:57 PM   #13  
Posted By: BFHFixit it seems to be a common problem in this application of this engine.

Sooo BFHFixit,

Did the customer just put this engine on this go cart ?

We use to be a Carter cart dealer and sold hundreds with the 60 and 65, I don't recall having any application issues with these engines on carts. The single biggest problem I had was kids playing with the governor springs/linkage to get more speed out of them, Every single one that comes in with run issues leaves running at factory specs.....

Fixed jet carbs are jetted to run with a certain air filter assembly in place, When one alters the air intake it also alters the fuel intake.

You started with a rich running carb, Altered the air filter (ran pre-cleaner only) which let more air enter to help disburse the extra fuel in which the engine ran properly.

Doing this shows you there is a internal problem with this carb (stupid check valve) since it will not run properly with the factory designed filter system in which the carb is jetted for.

These carts are designed to do only so much, If a customer wants to do more with them they need to upgrade to a larger cart or a ATV/UTV.

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

08-30-10, 06:37 PM   #14  
The unit is original including the engine from all I can see and the customer makes no claim of replacing the engine.

Essentially, all carbs are fixed jet carbs...yes? Some may have an air bleed that allows changing the fuel/air mixture? but the jet size is fixed?

I do understand how the mixture works and thus, my altering the air filter for testing.

A new carb is the first and one option I have informed the customer of, as well as printed your comments and posts for his info. Personally I still have a problem wrapping my arms around a goblin I have not chased before, and since I feel liable for a replacement carb if it does not solve the problem....well I guess I will get on the porch if I can't run with the big dogs...

I do thank you for your time and input,
Scott

 
31YTech's Avatar
Member

Join Date: Feb 2008
Posts: 1,263
FL

08-30-10, 07:23 PM   #15  
Well Scott,

All I've done is share the goblin I've chased and happily put my arms around, I understand 70+ bux would be hard to swallow not knowing for sure.

You could do like my local Chevy dealer did, Put a new instrument cluster and computer in my truck to fix my non working speedometer.....650 bux worth.

It worked for 12 miles till I got out of town then quit, Hit a bump and it would start working again. 'I' found a bad connection on a fuse in the panel, Think for a second they would take the new parts THEY installed back ?

Any who.... I'm a little too old to be chasing, I'd just as soon wrap my arms and move on to other things.... Beer 4U2


Good Luck with whatever you decide !

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

08-30-10, 07:42 PM   #16  
I understand exactly 31Y and by all means if I had access to ANY other tec carb to try, I would.

I just had a recent run about with a used washer I bought to put in the bathroom I just completely tore out down to scabbing up dry rotted joists.

Wife found a deal with a guy who said he gets used and goes through them checks them all out and gives 30 days. 75 bux ok, go get it bring it home and screw it over my new vinyl back in its hole, load couple towels in and start the cycles...all fine till its supposed to drain for the spin cycle. Pump just sits n hmmms. I can drain the thing full bore by lowering the drain hose to a bucket...call and argue a bit and he says fine bring it back he will look. Well he has his buddy tear the thing down in front of me, try it and sure nuff no pumpy, they search around for another pump put it ....no pumpy...I start asking for my money and let me be on my way this is only 30 mins later. They hmmm haw around and finally the guy working figures out he got the hoses connected backwards. So he messeses around gettin another hose on it and trying to mount the pump while I try and get my money back or another washer to look at or....
Well he got it back together and we ran it through and it did run out nice and was a decent unit so I drug it back home, back over my new vinyl and screwed it back into its hole. Toss some towels in and run it all good .....till.....drain ...hmmm well it drained but as it did there was also a brrrrr whrrrrrrrrr zzzzzz brrrrr coming from inside. Well I had noticed the changed pump had a small fan on it and the guy was having a time mounting it to fit the hoses, so I popped the panel and sure enough the fan was hitting on a brace for the washer when the pump was pumping water. Rerouted the hoses and put the missing mounting screw for the pump in and I think it will be a good lil washer....better be...

Sorry for the bantor but I do completely understand what your saying and I agree, you've not steered me wrong once and I don't imagine this time to be any different. It is the best option as I have told him, it just simply will have to be on his dime...

Thx agin
Beer 4U2

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

08-31-10, 12:42 PM   #17  
Posted By: 31YTech Sooo BFHFixit,

These carts are designed to do only so much, If a customer wants to do more with them they need to upgrade to a larger cart or a ATV/UTV.

I honestly think this is where it is, and the reason I am not so confident a new carb will give the performance he is looking for. I've rode dirt bike and I 4wheel so I am not timid with offroad equipment, and I have to push it pretty hard to make it stumble. My 11 yr old daughter can ride the thing for an hour and never once have a burp.
I think the kart itself is capable even if not intended for it and specifically with this engine.
If this was a tiller or pressure washer or some such, there would be little doubt of just what it should and shouldn't do....
This is meant to be a putt putt up n down the beach not a railer off in the dunes

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

09-08-10, 07:44 AM   #18  
Tecumseh # 640346 is not presently available and may not be for some time...
From what info I can find the original carb for this engine was 640025c, which has a primer bulb instead of the manual choke being the most notable difference. I can find a couple handfuls of these on e-bay.

Just curious if there was any other reasons for the succession?

 
31YTech's Avatar
Member

Join Date: Feb 2008
Posts: 1,263
FL

09-08-10, 06:29 PM   #19  
Hmmm...... Here's the successions I have;


640305 SS to 640346 which is where it is now.

640014 SS to 640004 to 640025 to 640025A to 640025B to 640025C which is where it is now.

There's no link/succession between the two, They are for different engine applications. But, Since both carbs are used on most OH195EA, OHH50,OHH55,OHH60,OHH65 engines I see no reason the 640025C wouldn't run this engine properly.


Cya

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

09-09-10, 08:13 AM   #20  
That makes as much or more sense
I have seen the manual choke version mentioned as a replacement for the primer unit.
At any rate there may not be any choice but to find out.

Thanx for the info.

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

09-09-10, 09:39 AM   #21  
Couple more questions?
Is it safe to assume that the other applications would use the same air filters?

I also found some after market carbs Oregon label, that are replacement for the primer type. I also noted that it only uses the Oregon overhaul kit, but otherwise was curious about their carbs. I have used Oregon parts with no issue just not the carbs.
Oregon no longer offers this carb either but are some on Ebay.

TIA

 
31YTech's Avatar
Member

Join Date: Feb 2008
Posts: 1,263
FL

09-09-10, 04:20 PM   #22  
Posted By: BFHFixit Is it safe to assume that the other applications would use the same air filters?

Yes you can assume so, Sorry I can't help with the Oregon carbs..... We use Rotary or Stens for aftermarket parts.

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

09-28-10, 12:56 PM   #23  
Ok what next?
New carb yields the same result. I left in the cut out air filter and old prefilter, cuz I kinda tired of soaking new air filters with fuel.
Took it out for a moderate spin, did get it to bobble once so back to shop and sure nuff, fuel in the throat and air filter housing....

 
31YTech's Avatar
Member

Join Date: Feb 2008
Posts: 1,263
FL

09-28-10, 06:46 PM   #24  
OK Scott,

I've been "mowing" this over a little now.....

With the tires off the floor and no air filter in place, Start the engine. Hold your hand about a inch or so from the carb throat then give it full throttle with your other hand.

Does the carb mist gas onto your hand ?

Is it enough to see it coming out of the throat ?

 
cheese's Avatar
Forum Topic Moderator

Join Date: Jul 2001
Posts: 16,567
GA

09-28-10, 08:44 PM   #25  
Thinking valves too tight? I am. Blowing back out the carb into the filter maybe.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
31YTech's Avatar
Member

Join Date: Feb 2008
Posts: 1,263
FL

09-29-10, 04:14 AM   #26  
Hello Mr Cheese,

Not so much as valves being tight since they are adjusted to proper specs, More like worn valve guides.

I just remembered a same model engine years ago that would run fine all day long until higher RPM's were reached, The higher RPM's would cause the valves to float around in the worn guides and not seat properly.

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

09-29-10, 10:29 AM   #27  
One of the first things I checked after the initial carb were the valve clearances and they were as noted in my first post.
What are the specs for this engine?

This kart and engine are showroom clean. No discoloration or build up anywhere. Not a knick, knock and barely any dust.

I performed the test 31YTech and did not get any misting on my hand, nor could I see any while shinning a light into the throat at full throttle.
Initially there was a film of fuel on the aluminum filter housing that bolts to the carb, I wiped that prior to testing and it did not reappear...

 
cheese's Avatar
Forum Topic Moderator

Join Date: Jul 2001
Posts: 16,567
GA

09-30-10, 01:39 AM   #28  
Yeah, I see that now... <smacking myself in the forehead>

I read the last post, then scanned the rest really quick and missed that bit.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
31YTech's Avatar
Member

Join Date: Feb 2008
Posts: 1,263
FL

09-30-10, 03:44 PM   #29  
Well Scott,

It really hurts me to say this, But I'm just about out of ideas on this one.....

Proper valve spec is .004 on both, I don't believe being .001 over on the exhaust is causing your issue.

With no mist (spit-back) out of the carb tells the valves are doing a proper job, The fact that fuel seeps from the carb and gets onto the air filter is leading me to believe the fuel level in the bowl is too high for this application (go-cart). I know it's a new carb and all but there's no other way for fuel to enter the intake or air filter areas other than through the carb.

Try lowering the fuel level in the bowl, There has to be a point you can get to that will reduce the fuel splash through the bowl vent and still have it run properly.......

 
BFHFixit's Avatar
Forum Topic Moderator

Join Date: Jun 2007
Posts: 1,762
KS

09-30-10, 04:46 PM   #30  
Well thx for the replies and help to ya's.
I will give the float level some more tweaking. I agree with your assumption, as long as I can keep it from leaning out in other conditions.
I also have no idea how the owner runs it. When I get it to bog I can tell it is loading up, and I feather the gas...without thinking...it passes and will take off like a rocket again once the load is eased.
I have tried to get him out here and test it so I could see just how and or what the problem is, but he a busy guy and this kart is for his grandkid....ne who..I plug at it a bit more then I guess just tell him I canot fixit....shame to cause the kart is really well designed and built IMO.

 
Search this Thread