Honda GCV135 with Keihin BB Carb - Surging Issue after strip

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Hi

I've read a couple of posts on here by Mark739 and Olneys.

Earlier today, I stripped down the Kehin BB carb and gave it a cleaning.

There was a great video on YouTube which I followed.

https://www.youtube.com/watch?v=V3S_7XpUioE

At 3:30, he takes a screw out and uses a rod to clean this jet/hole? out.

I used a bread tie and then a paperclip and I could NOT get it to insert into that hole much at all. 1mm. perhaps!

I used copious amounts of carb cleaner and even soaked in parafin for a while.

What does that hole do?

Also, in the video he shows pilot jet, screwed home and then backed out two complete turns. The manual stated 1+5/8 turns but when I removed it. I only counted 5/8 turns.

At first, the slow jet would not come out. It needed a good bash (carb in hand and hitting vertically down on tube which slow jet is in) to free it and allow it to come out. So this indicates it was well gummed up.

The slow jet was cleaned fairly well too.

All rebuilt but now the engine surges. I read a lot of articles on the net and tried various things.

When I sprayed carb cleaner onto packing gasket to cylinder head it smoothed out suggesting that there is an air leak but the gasket and body of carb has a routed air bleed.

Still pondering what could be wrong and what to try next?
 
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If the screw you are talking about is the one below the spring loaded tickover screw, its simply a drilling blank and the jet underneath is the pilot jet itself. The fuel flow through that is regulated by the anti tamper screw (1/3 turn).
You cant get fuse wire through the jet because the drilling turns 90deg immediately after the jet.
The emulsion tube (that falls out) needs to be very clean - you can see through the holes though.
Did you remove the idle jet screw, with the lead cap?
John :)
 
Hi burnerman

Looks like I have the professional advising me! Cool!

No not that one. I did remove the ant-tamper using a soldering iron to warn it first.

It is the phillips head screw to the left of that. If you watch that video I posted, which was by Seddons, it shows the guy rodding it with a sprung steel gauged wire.

Interesting you say 1/3 turn as the manual shot in the video states 1 5/8 turns for GCV135 and 1 turn for GCV160.

I screwed it in before removing it to see how many and it was 5/8 turns so I had a reference point to go back to if necessary.

According to Seddons, that is only an idle jet anyway so unlikely to affect normal running.

The emulsion tube did not fall out as it should. I really had to soak it in parafin and clout the end of the tube that goes into the float chamber many many times and hard to get it too shift. That in itself suggests it is really gummed up.

I could see through all the holes when I had finished poking it with a stripped bread tie.

"Did you remove the idle jet screw, with the lead cap?" Yes. See above but you already know that now!
 
Yep, we are talking about the same screw here......Phillips with a couple of dots on the head. It uncovers the route taken by the drill on manufacture.
With the anti tamper head on the pilot screw, adjustment is only possible for about 1/3 turn......if you can remove this screw, blow some carb cleaner down the orifice and the liquid will appear through a very small hole, just after the main throttle butterfly.
One full turn out on this screw is fine to get things going, as a rule......if there is a problem with the pilot mixture side of the carb then the engine just won't tick over but will be fine on full throttle.
Emulsion tubes sometimes are sticky, sometimes not......I usually shock them out by knocking the open base of the carb onto some timber. They only fit back in one way, anyhow.
Notice one or two holes in the carb face, where the air filter bolts on to? Get some carb cleaner in there too.
John :)
 
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Thanks John for continued advice.

I have lent it to a friend who is desperate in need of a lawnmower at the moment as he has set up a garden maintenance business. It is far better than the trash he has bought on GT recently.

He's had a conrod snap on a Mountfielf Empress and come through the side of the engine casing!.

I cannot confirm if head has two dots - memory tells me that is the anti-tamper - but memory is sometimes bad.

If the man on video rods out that one - why cannot I?

I've had carb cleaner in every hole that will accept it.

Seddons said bring it in to get dumped in the ultrasonic cleaner. Probably not a bad idea. Least evil of the options than replacing genuine and I do tend to be a sucker for genuine parts.
 
Just getting back to the original issue - the engine surging.
This is usually due to fuel starvation......the engine starts to slow down, so the governor calls for more speed so opens the throttle. The engine picks up, and the governor closes the throttle again so the revs aren't constant.
The big help with these is a supply of compressed air to blow through the various drillings and passages.
One point......passing the carb securing bolts is a bit of a far as they have to pass through various gaskets and a spacer. If one gasket slips,out of the way you get a large air leak that can give this symptom.
John :)
 
I think you're bang on the money there John.

I bought gaskets, air filter, oil and a new rope for it today.

I am not sure if the new gaskets actually helped because I stripped the carb down again and managed to get more carb cleaner through the 3 tiny drillings by the throttle plate. Only 1 hole was letting fuel through.

I am not convinced that they are 100% clear but more definitely cleared and it is running a lot better so compressed air next time and it should be bob on,

I think that the air filter housing has been overtightened at some point as it appears to be not quite flat where it meets the control plate so probably more air getting in there though before the carb so this probably wouldn't affect the running I guess.
 
Pleased that you are getting somewhere....!
The fit of the air cleaner box to the carb flange wont be a real issue (apart from some air missing the air cleaner, of course). Often enough, there are two tubular spacers inserted into the plastic to prevent distortion and they sometimes drop out.
Regarding the recoil cord, for speed I pull the cord out completely (assuming that it hasn't snapped) rotating the pawl disc, which I then jam so it cant spin back in. Then I cut the old cord, and insert the new so the recoil spring pulls the new cord back in.
Use a fag lighter to melt the end of the cord and pull it to a taper - it makes it much easier to thread back in.
John :)
 

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