Jason's mod questions

[RoyalStarRider]

Keep in mind I know almost nothing about these bikes (so far) but I have a vast background in building cars so I'm not completely stupid.

 

I've already started doing a few mods to the RSTD but I have a couple of questions that I couldnt find the answers for.... and yes I searched.

 

Mine is and 06 and it has cruise control and I've already done the AIS plugging and Jasons mod.

 

Now when I did Jasons mod I connected both runners on each side... but in the write up it mentioned I had to T into 1&2 to keep the cruise working, also it mentions T-ing into 3&4 for the ignition module to work right....

 

Does the 06 need both of these or did I do extra plumbing for nothing??

[pegscraper]

The ignition module does not use manifold vacuum, it is controlled by a TPS on the throttle shaft.

 

My experience is that the Jason mod does nothing more than make the engine idle rough. Supposedly it emulates the V-boost system in a VMX, except that the V-boost valves are 32mm and these vacuum lines are less than an 1/8". That's not big enough to do anything more than act like a vacuum leak. IMO you did it all for nothing.

[Condor]

I did the Jason mod to the '83 and really couldn't tell any difference in performance. Rode with it to Ft Collins, and rode back home without it. 1100 miles each direction. No difference in gas milage. When I got back I put it back on because it gave the bike a little attitude and got rid of the sticato idle. It gave the motor a little lope which I liked. I'll do the mod on the '99 when I get around to it.

[SaltyDawg]

I have done the Jason Mod to both my 99's and yes it does make it idle a little rough.

 

I noticed about a 2 MPG increase in both bikes, and better low end response. Others have had varying degrees of good, bad, and little or no change.

 

I can only attest to my experience.

 

Now the ONLY thing that made a very noticable increase in fuel mileage was a "ColorTune", followed by a "CarbTune"

 

I have had the CarbTune done and noticed an increase in mileage, but the ColorTune made a significant increase. I'm talking close to 10 MPG. Went from low 30's MPG to low 40's MPG

[RoyalStarRider]

Well my bike already had a very lopey idle prior to doing anything to it... almost like someone had put a set of cams in it. As for mileage I managed 40mpg on the first tank and havent ran the 2nd tank out yet.

 

The Jason mod to me reminds me of setting up duel Kadrons on a VW motor... from the factory they had a hose that ran from on side to the other and its purpose was to equalize the carbs. I'm thinking about "modifying the mod" and run a crossover tube from on side to the other..... along with opening up the vacuum nipples for increase flow capability.

 

Either it'll work or it wont and if it doesnt it only takes a few minutes to reverse everything that I'm going to do.

[RSTDdog]

Well my bike already had a very lopey idle prior to doing anything to it... almost like someone had put a set of cams in it. .

 

Have you checked the Carb Sync yet?? When they are in Sync and everything is stock the idle is pretty smooth.

 

I would make sure it runs perfect in stock form, then start making changes.

 

I have not done the Jason mod so can't comment on that. To me its really Half a YICS and not really comparable to V boost at all.

 

Tying all four together like you are suggesting is most similar to the YICS ( Yamaha Induction Control System?) from the 1980's. Yamaha inline fours used to have all four intakes tied together via a casting through the cylinder head. I do not remember the marketing hype about it at the time but I'm sure Mr. Google does. That port going through the head was like 3/8-1/2 inch IIRC. There was actually a YICS block off tool to block the ports so you could properly Sync the carbs. Once synced the tool is removed and the intakes are connected with each other. The connection is after the throttle plate so it should provide balance and compensation for minor differences in vacuum. IT also adds volume to the vacuum side of the intake tract.

 

The Early Ventures (Ist gen)had a version of YICS that used plastic boxes to tie the intakes together. The boxes would split and leak and cause rough running and most people removed that. If there were any real benefit to YICS or tying the intakes together, (fuel Economy, emissions reduction, performance, etc) IMO Yamaha would still be doing it.

 

No matter what mods you do its always good to establish a baseline first. Let us know how you make out.

 

RSTDdog

[RoyalStarRider]

Well I went and synced the carbs and it runs alot smoother than before and its also more responsive.