A few more questions

B

Bob Vehring

New member
Joined
Dec 10, 2008
Messages
114
Age
73
Location
Milw. Wi
Does anyone know the ID of the water hose's, trying to avoid a water mess until I can order the inline sensor I need.
Also I assume the 12 v power is AC or does it already have an inverter to convert to DC
 

Also, I have seen several references to gutting the airbox, our sled just made it into the shop for the first time tonight, I have had the air box off before, but not taken it apart. Is this something worth doing, or should I leave it alone?
 
Thanks Doc, already removed the white parts, will route vent hoses to it also. Right now sled only has PSI pipes
 
Well still have to put in the picks, and not looking forward to it, have to make it faster then my 83, so far his mother has beat him twice. I just love starting family wars.
 
I use to run long vent lines to the bars. Now I just drill 4 holes in each air box and push the stock vent hose into them just a tad. Make the holes interference fit so they dont fall out. Long hose would sometimes hold fuel and run funky.

I think I ran 140mj with PSI quads, vent tubes to air box, sea level on 750.
 
How sensitive to temp changes are these carbs seems were stuck in the mid 30 here for the next two weeks, I'm 650 ft Should I still shoot for 1200 deg or so with this one?
 
Don't get focused on EGT. Whos EGT, fast, slow read, placement, fuel, timing.. All problems
The only 100% true exhaust temp limit is after your sled burns down, thats to high.

Read plugs and wash. You could swap 140mj to 142.5 and only drop 1.5hp off PEAK. Be low grade pump gas safe and only see a 1% drop in hp.
BUT your over rev hp drops by 10hp or more (140mj vs 142mj). So if your clutching is rev happy, you feel rich jetting.
If you pull the rpm down a bit, ride the tq curve and wont need to run on the edge
 
Well, I'm just learning this sled, I do run Aim / MyChron systems on a everything I have. It will plot jackshaft RPM against Engine RPM and shows a clutch graph for every run, so I can read clutching.
We have a bore scope, piston is black and covered, was a trail sled. Doubt I can see much there for a while.
I feel comfortable with EGT, fast response probes, and they download to laptop in trailer, I can view the entire run as a line graph. I also have A/F capabilities if I put a batt in the sled,have extra sensors here, hope to get to that before this first Radar Run but running out of time.
If it ever snows in SE Wi again sled will see the trails some, which is where I really like the data system, never trust pump gas around here.
 
don,t pull away fuel from a vmax4. big mistake. 1500 egt would be load on trailer time in my book. now with that said you can drop back a little. and those carbs are not sensitive , but again all depends. use your basis jetting skills, all ya need. 3:16x (yammie tony)
 
The 1500 wasn't my number I'm just looking for a range of jets I need to order,I have nothing for these type of carbs Have boxes of round slide stuff, just need to stock up here before we take it out the first time
 
Bob Vehring said:
Well, I'm just learning this sled, I do run Aim / MyChron systems on a everything I have. It will plot jackshaft RPM against Engine RPM and shows a clutch graph for every run, so I can read clutching.
We have a bore scope, piston is black and covered, was a trail sled. Doubt I can see much there for a while.
I feel comfortable with EGT, fast response probes, and they download to laptop in trailer, I can view the entire run as a line graph. I also have A/F capabilities if I put a batt in the sled,have extra sensors here, hope to get to that before this first Radar Run but running out of time.
If it ever snows in SE Wi again sled will see the trails some, which is where I really like the data system, never trust pump gas around here.
Click to expand...

Nice system. You will need to find a way to adjust motor rpm signal to show primary clutch rpm and not motor rpm. Vmax 4 is PTO driven and not 1:1 drive. At full lockup it may still show some slip vs driven, but its actually the gear reduction.

EGT, A/F are all after the event (powerstroke). Like a black box after a plane crash, lots of stuff to read as it went down. Four stroke guys can really tune with this info. The have twice as long to read it and adjust (4 strokes vs 2) and way more range to work without hurting the motor.

Two stroke we need air flow, fuel flow, BSFC.

Just my .02 anyway
 
Great point on RPM, will have to look if I could mount a second speed pickup down on the shaft.BTW, we are 4 stroke engine builders, but don't hold that against us LOL
 
Nice stuff Bob. Id like to see some graphs when your done.
Id run polaris 10-64 and HPE orange in the primary with PSI quads. I didnt have any luck with that driven. Tony does so Id go with his advice. I chucked my stock driven in 93 and never went back. Started working with Cat and Lencco back then.

Whats the part number on your CDI
 
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For years my kid ran Pro Sprint 600 and F500 in USSA ovals, our engine guy set up the clutches, he's a Pol. clutch guy. I know it has almond/red spring, have to look up what Gram wts we ended up with, tried quite a few sets, that was 500 ft grass and it had Reichards quads then. Have most parts in the trailer.
We started using MyChron/Aim stuff in kart racing back in mid 90's. It came in as a replacement from Digitron that everyone used then. This is the EVO4 system we had on the race sleds and can do almost endless channels, I use the systems right off our karts on my other trail sleds Those can do several temps, speed and have integral tri axial accelerators in them, newer ones also have GPS Those new are around $500. In our business Kart and 120 race engines, I simply have customers email me their files of race day and we can see everything that happens in their engines. Makes life easy for customers from far away.
 
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