Idle High after Carb Clean and rejet.

[VerntureVet]

88 venture royal.

 

Straight drag pipes

Stock collector

Stock air cleaner with KN filter

 

So she was popping after hard WOT or heavy throttle say in 3rd and then letting off the gas, with power loss when WOT as the mains kicked in. I got me some 135 main jets and gave the carbs a nice cleaning.

 

After getting her back together I backed the Idle screw all the way off the stop and when warmed up it is sitting around 1300-1400. When blipping the throttle it is slow to come back to the 1300-1400. I can get moving in 1/2 and let go of the throttle and it will idle in gear and not stall @ 1000RPM. The popping when coming off heavy throttle is gone and the bike feel like it wants to rip the asphalt right off the road when @ full twist. The Flat low power pull I had when in 4/5th WOT is gone and the bike wants to just throw me off the azz end from the powerful pull.

 

I thought maybe a vacuum leak but went threw an entire can of carb cleaner spraying around the intake and carb with no noticeable change in RPM. i have messed with the pilot screw and synced it 20 times. Other than the higher than normal idle it runs like a rocket on 2 wheels.

 

Any feedback would be great. Only thing I can think is that with the drag pipes and new jets she just wants to idle faster like a crotch rocket. Or I could be laim.

 

What do you guys think?

[Great White]

Sounds like rich at idle...

[Great White]

Sorry, I c@cked that one up.

 

Sounds lean, not rich...

[VerntureVet]

  Great White said:

Sorry, I c@cked that one up.

 

Sounds lean, not rich...

 

I figured it out. @ first I was disappointed because I went threw all this math to choose a ball park jet pack. I got out on it this morning and figured I would unshim my needle because I am Jetted up and maybe the needle shim was too much with the bigger jets. A long shot since it was a idle high idle. I found that I forgot to tighten the diaphragm cover screws on one of the carbs. I want ahead and un-shimmed it any how. I also put back on the semi-unbaffled mufflers. All that brought it back in line.

 

I think I made too many changes @ one time so I will roll the way it is now for a week and maybe see what putting the shims back on do for the pickup they seamed to give with the stock jets.

 

I find these Mikuni carbs to be super temperamental when you change flow rates. I still want to change the air intake and filter box but the carbs do not appear to like more air.

 

On a side note I have ordered a Microprocessor for winter month experimentation of building unit that will allow for monitoring the pickup coils, MAP, Mass Air, RPM, V-Boost Position, and TPS. If time permits over the winter I hope to be able to monitor conditions and how they affect the engine running. Ultimately I want to integrate a Mosfet driven ignition.

 

But I have to figure out these carbs and there little quirks. I have never worked with MC carbs nore have I ever messed with a carb that just hates air so much. I am almost to the point of adapting a holly 750cfm 4 barrel and seeing what it will do lol.

[garyS-NJ]

sounds like interesting work with the purposed micro-p and the fet ignition.. I only found one aftermarket ignition for these bikes (Ignetech) and I'm in the tweeking stage (crappy throttle response.. but could be carbs).. A good system monitor would be gold for setting up this ignition.. Modern car and truck ignitions work with sensors to do great stuff (cover up all sorts of problems). I'm also looking to get my stock '84XVZ12D breathing better but need to work on throttle response before touching intake and exhaust.. I'd like to take it in steps by changing the stock mufflers to low restriction and a hot intake filter without rejetting.. If I need to rejet for that then I would rejet for with fishtail pipes and IDK on the air filter..

 

this link and the XJ4ever forum helped me figure out why my XJ 550 was sometimes not quick to idle down (I think it was a choke circuit issue, but I forget). I cleaned carbs (they were clean from regular riding) and rejetted (for pods and open collector) and the bike runs great and idles back down..first shot (and only did a gross bench sync).

 

http://www.factorypro.com/

[VerntureVet]

@garyS-NJ I did some experimentation over the last few days. I was able to get a Raspberry Pi on a lawn mower engine. The breakout board I have uses relays and they just can't keep up over ~3000 RPM. good enough to switch a Mosfet and run a lawn mower engine. But I will need to get a different board or MOD this on to direct fire the mosfets instead of firing them with the relay.

 

Promising however because all I did was put a hall on the flywheel and fire the ground to a coil and it seams to work great. I moved on to the carb and removed the typical air flapper that speeds the engine back up under load and replaced it with an RC car steering servo. With that I was able to write a script to change the spark advance and trim the engine speed based on engine RPM. I then moved onto installing a servo on the throttle control and used a 1/2 turn pot as a sort of fly by wire throttle position. Its a balancing act in the script to get thing right all the time but I am sure more code can get me what I want. The Mower actually runs better now than B4. I bet with a wifi card and some slick programming I could even get ti to start with an android App.

 

It will be some time before I attempt this on the Yammy but it looks promising and the Raspberry PI should be able to control everything from audio to turn signals if set up.

 

Also as far as aftermarket ignitions the MegaSquirt is pricey and will take some doing to get it to work without the EFI part of it. the Ignetech is a great unit and a few here are using it but if I am not mistaken it can only be set up for either TPS or MAP. I am looking to monitor MAP, MAF, TPS, A/F mixture, speed, and RPM and adjusting spark and advance with those inputs being considered. I don't know if the carbs will like it too much. who know by the time I am done I may just put on the V-Boost and 3D print an intake and make her fuel injected.

[Great White]

Correct on the ignitech.

 

Its an either/or proposition between MAP and TPS....

Edited September 30, 2015 by Great White

[VerntureVet]

  Great White said:

Correct on the ignitech.

 

Its an either/or proposition between MAP and TPS....

 

Thanks for confirmation @Great White. I do just want to break down and get the Ignitech but I can't help but feel that even MAP + TPS could pull the 1300 into a new realm. I have been looking @ the Microsquirt unit. They have confirmed with me that it can be set up without the EFI enabled and just use the Coolant temp, TPS, Air intake temp and spark and advance timing curve. They assured me that Microsquirt can preform as well as Ignitech but it is able to have O2, MAP, and MAF added latter down the road for even more control.

 

On the flip side my riding mower is now run off the Raspberry PI ignition script I messed with. Its kind of nice actually 100% drive by wire now with GPS, bluetooth MP3 and Wifi now. Maybe I will mess around and put on a servo motor for the steering and see if I can GPS mow from my lawn chair with the Android. Just digging for a cheap 7in touchscreen for it :-P. By the time I learn the ins and outs of this Raspberry setup it should be just a matter of tweaking the multi outputs and have it fire the Yammy. I can't wait to get it on the yammy But I need to learn so I don't burn the bike.

[Great White]

Not so sure on a carb engine of the need for all parameters.

 

Spark control is actually quite simple.

 

Tps for advance (same function as a centrifugal dist), map to pull advance for load and a knock sensor to pull advance for knock is about all that's needed.

 

You start getting into the rest for fuel control.

 

The early "electronic carbs" from the early 80's (just prior to speed density TBI systems) only had map and tps for spark control as that's about all that is needed. There's only so much you can do with spark control alone.

 

Still, I wish the ignitech had both and not either/or.

 

I've always found maf to be more of a PITA than anything else. Speed density has always been more friendly to "tuning". The maf itself is often a constraint that is hard to overcome when talking hp.

 

Maf works fine for a driver, but speed density is better/easier for modifying. IMHO that is.

 

I pretty much dropped gassers a while ago. Same as I dropped obdI tuning. I mostly do diesels in obdII these days. Power is there for the taking with just fuel and timing......big power. None of that scratching and fighting for 5-10 hp gains on a Gasser. Zip up the fuel and boost, adjust timing and grab another 25-50 hp with no other changes and still not oberstressing the rotating assembly. Yeah, that's the ticket!

 

 

If you're thinking of going microsquirt and FI, you're in for a long road. Lots of buggering around just to get the spark and fuel tables right for driving. Then there's the enrichment tables, etc etc....

Edited October 1, 2015 by Great White