Opsled! What do you think of this porting job?

jipcee · Post by **jipcee** » Wed Nov 12, 2008 12:09 am

Any thoughts on this porting job for my 83 V-Max.
Updated porting specs were done. Lower transfer ports also opened and general cleanup. Also going to 44's
Thanks for your comments or criticisms.

Post by **Vmax540** » Wed Nov 12, 2008 8:13 am

Looks like a job done well. My first thoughts are is this setup only for racing, or do you want to trail ride ? I have never ran a 540 with the updated porting let alone any that were pushed futher but, I have heard from several over the years that anything beyond the Yamaha recommened specifications setups and reliability/trailabilty suffers ? The following concerning carburation is from the Articles section. Please give us upates when the snow flies !

1986 Updated Porting
Regarding the carburetion on the update port V-Max, the stock 38mm carbs are all the engine requires. Larger carbs will not increase airflow or horsepower on this engine. This is similar to a Wildcat, which developed the same airflow and horsepower with either 38mm, 40mm, or 44mm carbs.

jipcee · Post by **jipcee** » Thu Nov 13, 2008 1:36 am

well, last year I ran the sled with just the update porting and bored carbs to 39.5mm when i finally got it tuned It flew!
We have 3 V-Max's we ride with and my sled put over 100 feet on enerybody before we hit 90mph, we all ran pretty even before the update porting.
This is just an experiment to see what it does.
Thanks for your observations and help!
Opsled what do you think!
thanks..............jipcee

vmax-540 · Post by **vmax-540** » Thu Nov 13, 2008 10:39 pm

I used to have a set of update ported cly. on my Vmax and they really do wake that sled up. But mine had the stock 38mm carbs.Yamaha almost put that porting on the 83's but at the last minute changed it to what we have today ,they didn't want an other 81 on there hands , it's to bad because it would have made a great sled even better. I know that the Formula III porting had 44mm carbs and cut pipes. Looks like you did a good job on the porting..

jipcee · Post by **jipcee** » Sat Nov 15, 2008 12:14 am

vmax-540 wrote:I I know that the Formula III porting had 44mm carbs and cut pipes. Looks like you did a good job on the porting..

Thanks for the comments..........

I've never heard of "formula lll porting, Can you remember any of the changes or are they available somewhere. It would be awesome if they were in writing to compare.

Also, you are right the update porting REALLY woke my sled up. Last year I did the update porting to specs and also cleaned up the intake and exhaust port. I also made the exaust port exit a little more oval (wider).

If you look at my pictures you can see the flat spots on the intake port on the original cylinder. I ground those down and you blend them with the flow of the rest of the port.
The port window size in the cylinder should not be changed. There are flat spots on the exhaust port too that I ground and blended.

My father-in-law, my son and I ALL ride V-Max's together and before my porting we all ran damn near identical, after my update and port job and bored to 39.5mm carbs I am not kidding that I now put almost 100 feet on the 2 other V-Max's by the time we hit 90mph.

I spent all of last year jetting the sled and finaly ended up with these changes.

Before
290 Main
110 Power
35 Pilot
6DH10 Needle
Q-0 Needle Jets

After
300 Main
140 Power
35 Pilot
6DH1 Needle
Q-4 Needle Jets

As you can see I really had to add the fuel.
I use digital exhaust temp gauges to jet the sled.

..................................jipcee

Marc Machine · Post by **Marc Machine** » Fri Jan 09, 2009 9:28 pm

could you give me the information or tell me where I can find it regarding the updated porting specs? Thanks.

jipcee · Post by **jipcee** » Sat Jan 10, 2009 1:17 am

They are in the article's section "1984 Update Porting Specs"

Post by **tyler440** » Sat Jan 10, 2009 11:12 am

thanks jipcee!

opsled · Post by **opsled** » Sat Jan 10, 2009 4:27 pm

I don't know how I missed this thread when it was first posted but your job looks great!!!! It sounds like you are getting it dialed which can be a real headache sometimes and is often where most of the work comes in. I'd be interested to know who did them for you or if you did them yourself. I'm not a big fan of yellow (for obvious reasons) but I like what you have done with the paint (COOL!!) and would also love to see some pics of the sled.

I see you're in Chicago and I'm only an hour or so north of down town so we can't be too far apart. I still have plenty of of parts so if you need anything let me know.

Again NICE WORK!!!

Phil, (opsled)

jipcee · Post by **jipcee** » Sun Jan 11, 2009 12:35 am

Opsled, I live right by O'hare.
I know exactly where Burlington is we used to run up the fox river from the chain.
We got 12" today, I know you guys got pounded too.
We go to the "chain of lakes" when conditions are good.
I did the update porting and cleaning of the intake and exhaust ports.
A friend of mine did the lower transfer ports. He knows his stuff.
He did a set of jugs for Bender back in the day.
So far jetting the 44's is proving to be quite the challenge.
I'll keep you posted.

jipcee · Post by **jipcee** » Wed Jan 14, 2009 1:25 am

UPDATE!
Well got the sled out sunday, I put the bored out 38's back on and upped the jetting 25 on the mains. Got the jetting close, WOT = 1275 degrees left cyl. and 1225 degrees right cyl. I'll go up 5 on the left.
We hooked up with a guy that had a 01 MX-Z 800 with a pipe and clutch kit. He ran to the next town with us and we got to race at least 6-7 times. Conditions were not that great and could only run up to around 90mph when we ran out of field.
From 0 to 90 I stayed right next to him the whole time.
I was pretty happy with the results, 540 vs. 800 dead even = "SWEET"
I have the bored out 38's dialed in so now I'm going to work more on the 44's.

Joe · Post by **Joe** » Wed Jan 14, 2009 3:06 am

What is a good EGT reading at part throttle?

My Polaris is running about 1450 at part throttle and 1200 at WOT.
The pipes are getting rusty like I have never seen before.

If I richen the midrange to get the temperature down, It developes a serious mid range bog.

I wonder if there is a clutching issue.

I plan to move the EGT gauge to the VMAX in two weeks to fine tune it's jetting.

I'm practicing on the Polaris so I have some experience before I tear into the VMAX.

jipcee · Post by **jipcee** » Wed Jan 14, 2009 7:30 pm

Joe wrote:What is a good EGT reading at part throttle?

My Polaris is running about 1450 at part throttle and 1200 at WOT.
The pipes are getting rusty like I have never seen before.

If I richen the midrange to get the temperature down, It developes a serious mid range bog.

Usually if you run more than 1300 degrees for an extended amount of time (more than 10-15 seconds) you are real close to melt down.
If you've been running 1450 I would say your gauges are not accurate.
I always check the accuracy of my gauges every time I start to jet a sled.
I check the reading on gauge compared to the spark plug color.
A reading of 1250 on the gauge should show a tan color (like cardboard) on the spark plug insulator. If it is black your gauge is showing to high of a temp.
To get an accurate plug reading you should run the sled at a given throttle opening, (say half throttle) holed at half throttle for 10 to 15 seconds, and with your left hand hit the kill button. Leave throttle at half until the sled comes to a stop. Pull the plugs and check the color.Also just before you hit the kill switch look at your gauges and remember the temperature.
Now you can compare gauge accuracy to plug color.

Joe · Post by **Joe** » Thu Jan 15, 2009 4:15 am

The gauges are new.
I did not suspect that they might be out of calibration.
I will check the calibration on my next trip.