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2007 AC pump timing - not adjustable?

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2007 ac pump.jpg

 

hi guys,

 

i am building a baja bike for this years 1 k and am running into a slight issue... the dreaded off idle bog...

 

i have searched all the related posts on TT and have done the following mods

 

- cut top off airbox

- NCVS needle

- merge spring

- 08 AC pump kit (since replaced with r&d adj leak jet, however 08 rod, diaphragm, spring still used)

- r&d flex fuel screw (spring washer and o ring replaced with brand new)

- 48 pilot, then 45, 48 and finally back to 45 (48 was brand new, 45 was original but carefully inspected)

- 165 main

- pink wire mod

- float bowl check valve removed

- fishing line and wd 40 through pilot and fuel screw circuit

 

other mods 

 

FMF power bomb exhaust

New top end and cam chain

vapor computer (accurate RPM check)

 

 

So over the last few days I have had the carb in and out a few times trying to resolve the off idle bog. This bog only happens in first gear and when under high traction. When im on loose soil the bog is not noticeable (which makes me think im chasing a PERFECT set up, feel free to tell me to STFU and ride )

 

The issue thats concerning me is that I have the adj leak jet turned all the way in (most fuel through the nozzle)...seems like this would indicate that something is wrong with other circuits. it runs pretty clean like this, but there still is a slight hesitation.

 

I have been reading notes from the JD leak jet kit instructions about ac pump timing and was thinking this may be the only item i havent considered, but looking at my FCR it looks as if there is not adjustment capability....see pic.... The squirt is pretty good, 6 ' solid stream, straight, around 1 second, not hitting slide - however I thought i could get it a millisecond closer if I could adjust the timing.

 

Any thoughts? Much appreciated!

 

 

 

 

 

 

 

 

 

 

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You can see the threaded portion touching the blue lever.....that is the adjustment screw. The head of the screw is goofy, and you can either purchase the 'D' tool to adjust it,  or just use a solderless connector jammed over the end, as a 'knob' to turn the screw. You can also modify the head, once removed, with a strait notch, for future adjustments.

 

Be sure to watch the squirt (engine off!) to view it's quality.

It should shoot all the way into the left side of the head, for 1 second, with a hard twist and hold throttle, just barely missing the slide.

 

Sounds like everything else is fine.

 

You will always get a slight bog if you try to look for it. 

Edited by Krannie

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That's correct, in '07 Honda put in a non-adjustable AC pump... Your setup sounds good, except the adjustable leak-jet. I'm not a fan of these, I would go back to a pre-set jet, and try a 50 to start and go from there. Also make sure you put all the springs, diaphram and O-rings in correctly. Also be sure that you have no obstructions in the pilot circuit.

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Thanks for info in adjusting that screw. I will try later. Krannie - I took a video of the squirt and noticed that it shoots into the right (when looking from behind carb) side of the head. If it was to hit the left side I would think it would hit the needle no?

I have tried 50 and 45 leak already but they didn't seem to affect anything.

Would it damage anything if I completely blocked off leak with plug and went back to 08 pump cover?

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Blocking the leak jet is recommended by some.

I like to be able to drop the squirt duration at high altitudes, so I leave it, or use an adjustable leak jet.

If you still have a bog with normal riding, it's probably time to check your intake valve clearance.

You will never remove all the bog for all circumstances.

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Thanks for the info guys! Your support thru thumper talk is excellent.

I did check the valves. All good. .011 and .006.

I took to local honda shop as I am turning up nothing for solutions. I will report back on what they find.

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The TRX carb has the same adjuster. I just cut a screwdriver slot into it with a dremel cut off wheel. Works great.

 

I just realized, Krannie already suggested it.

Edited by MasterT2000
  • Like 1

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Well I took the bike to a local shop with no resolve. They tried all the various combos of ac pump diaphragms, rods, leaks, needles, taping off cut airbox, ap timing.

I have come to believe that krannie is on the right track with starting to look elsewhere for the issue.

I since took the bike to a dyno tuner tht specializes in bikes, atvs, and sleds. (Nice find!)

Right away he said we should look at valve train timing as I did replace cam chain and top end. He says you can be a tooth out and it still runs decent. Can anyone confirm this?

Thanks

LE

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The symptoms are when opening the throttle wide open off of idle it just chokes itself out. Idles fine. Power seems to be decent throughout range. Starting to notice more decel popping.

Here are current mods -

Fmf mega bomb

Cut top off airbox (not really that much)

Ncvs needle

45 pilot

165 main

R&d alj(with plug in place of stock leak)

Merge spring (07 carb w blue linkage)

08 ap diaphragm and spring, rod

Removed check valve from bowl

Stock air filter w belray oil

R&d flex screw ( usually 2-3 turns out)

Kibble ss valves ( put in over a year ago)

Current elev = 2500 ft

Ambient temp range = 10-20 deg c

I just replaced piston, rings, cam chain, cam chain tensioner, adjusted valves to .011&.006, new gaskets.

Could I really be out a tooth on cam gear with a decent running bike?? Any other typical screw ups during top end rebuild that would result in bog?

Tps? I never touched it though.

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First of all, are you testing this on the stand, or during actual riding.

If it 's on the stand ignore it. It means nothing, unless you are not trying to do it as fast as you can.

Use your thumb and index finger.

 

You want to test at a reasonalbe rpm as well, when riding.  That will assure you you are not just over-loading everything because you are in too high of a gear.

If you are in 4th gear going 35 and you 'whack' it, it supposed to bog a bit.

 

 

My bike is jetted to perfection, and i can make it 'quick throttle bog' in tons of situations....none of them having anything to do with the actual throttle needs, while riding, because that amount of throttle at that instant is too much for the motor/load/rpm

 

I'll post a video...

  • Like 1

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What krannie just wrote is so true. That being said if it is doing it in riding conditions it is possible to b off a tooth on you cam. On my trx I was able to move a tooth and not experience horrible running conditions. Only difference between us is I had decked the head so my timing was retarted when trying to set it correctly. My fix was a adjustable cam gear. Now I'm not saying that is what ya need I'm just saying it is possible to be off a tooth and it still run.

Only takes a few min to rule it out too .

Edited by StonedInNy

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Thanks a lot for the video! It's good to know that a perfectly jetted bike will still bog.

I would post a vid of mine but its at the dyno tuners right now. Ill post when I get it back along with my dyno results.

I appreciate the time you took to film and upload those krannie!

And stonedNY that's for the confirmation on cam position.

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Thanks a lot for the video! It's good to know that a perfectly jetted bike will still bog.

I would post a vid of mine but its at the dyno tuners right now. Ill post when I get it back along with my dyno results.

I appreciate the time you took to film and upload those krannie!

And stonedNY that's for the confirmation on cam position.

 

 

Please call my neighbors  for me and explain it, would you??

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Well after $1100 of labor costs I have figured out what the problem was, well combination of little problems.

The owner of accurate dyno tune in Sherwood park , AB solved this issue.

Ac pump timing - even though it looked good to me and tech at honda dealership, it was too slow. I don't have the specs on exactly what timing is but it starts squirting as soon as slide starts moving. He said possibly hitting the slide just a bit.

Ac pump spring - the merge - looks like either me or honda tech ( not sure if he moved it) put this spring in improperly. Rookie move I guess. It seemed really tight to me but I guess it still could get into a tighter position.

Fine tune - he adjusted the leak, fuel screw, idle properly.

Then I got a dyno test on it. Trying to ensure its going to be good for the Baja 1 K coming soon. It's hard to predict with our current elevation, humidity and temp but looks like I should raise needle clip one. Looks lean in the beginning, but he didn't point this out as a big deal.

Ill post dyno results if I can. 50 rwhp.

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