I know I will get it sorted...eventually!
It reminds of my dad's slower '85 where we couldn't find the missing power. I will be fairly methodical, and get it sorted out. On the plus side, it sure will be fun when I find that missing hp. :biglaugh:
Help Support VMAX Forum:
I know I will get it sorted...eventually!
It reminds of my dad's slower '85 where we couldn't find the missing power. I will be fairly methodical, and get it sorted out. On the plus side, it sure will be fun when I find that missing hp. :biglaugh:
Based on the dyno sniffer, it's definitely not too fat. It is a bit leaner than I run my FI bikes, but nothing so major as to account for 30 hp! When I get my aftermarket pipe, I will put a data logger on the bike, and some 02 sensors. But for now, it is going to have to be the old-fashioned way of tuning/troubleshooting.
Last edited:
Found one problem already!
When I got the v-boost from Patmax, he was very kind to assemble the setup, so I would have a guide as to how it went in. That was a big help!!
He also told me to adjust it, per the service manual. Well, I was so anxious to try it out that I skipped that little step. I have just found that at the full extent of the servo's operation, the valve is only about 2/3 of the way open. I will adjust everything per the service manual, in the morning. Then I will change the plugs and take it for another ride. I won't likely be able to try it on the dyno for another week, though.
When I got the v-boost from Patmax, he was very kind to assemble the setup, so I would have a guide as to how it went in. That was a big help!!
He also told me to adjust it, per the service manual. Well, I was so anxious to try it out that I skipped that little step. I have just found that at the full extent of the servo's operation, the valve is only about 2/3 of the way open. I will adjust everything per the service manual, in the morning. Then I will change the plugs and take it for another ride. I won't likely be able to try it on the dyno for another week, though.
One other area I was concerned about was the clutch. But looking at the data from the dyno runfiles, you can see that there isn't any significant slippage:
The nice thing about a Dynojet dyno is that you can go right to their site and download the Winpep software. That will let you analyze the raw data from the dyno pulls, as long as your dyno operator gives the .DRF's to you.
The nice thing about a Dynojet dyno is that you can go right to their site and download the Winpep software. That will let you analyze the raw data from the dyno pulls, as long as your dyno operator gives the .DRF's to you.
For those who are interested in messing with your own .DRF files, I posted this in another forum, a while back:
Anyway, it is easy software to use. It can be a valuable tool!
A few people have asked me about the dyno charts that post, what software I use, etc...
If you have your bike run on a Dynojet dyno, there will be a "runfile" generated with all of the data from the run. This ".DRF" file can then be loaded into the Dynojet Winpep software and you can analyze your runs, or capture the screens, and/or print them out at your leisure!
Here are some basic Winpep screens:
Here is the page where you can download the Winpep 7 software:
Dynojet Research Inc. - Software - Downloads
And here are a couple of sample "DRF" files that you can play with (Right Click, "Save Target As" to download):
Sample DRF 01
Sample DRF 02
The runfiles are nothing special, but you should be able to try out some features of the software by using them. There are many features of the sofware, I just use the basics. :thumbup:
Anyway, it is easy software to use. It can be a valuable tool!
Rand-5107
Well-Known Member
Since you are pulling your plugs, a compression test might be in order.
![Bovemanx Motorcycle Phone Mount Holder, [150mph Wind Anti-Shake][7.2inch Big Phone Friendly] Bike Phone Holder, Motorcycle Handlebar Cell Phone Clamp, Compatible with iPhone 16 Pro Max Smartphones](https://m.media-amazon.com/images/I/51F+1sontPL._SL500_.jpg)
cgswss
Well-Known Member
What worries me about the dyno run is the way the engine falls flat on it face at 8800. Every pull on a stock Vmax I have seen pulls to about 9500. If you could adjust it, I would say try advancing the timing, but on a max, it more like replace the module. It there any chance it has a Dyna box in it? While I would like to see the compression too, I would look at the spark box first. If you had weak valve springs, I would think you could hear the valve float when on the dyno. At any rate, you have something wrong beyond just jetting.
cgswss
Well-Known Member
This is more like I expect in a stock engine Vmax dyno (although this is for after market pipes)
http://www.holeshot.com/old/vmax/vmx_4-2dyno.html
http://www.holeshot.com/old/vmax/vmx_4-2dyno.html
I think I have found the culprit(s). First, the v-boost was out of adjustment. On this particular set, I needed to adjust it about to it's limits to get a good setting at full open:
Presenting: The 3-Max
Anyway, I did manage to get the plugs swapped on it last night. When I removed the old #1 plug, it was wet. So that was on my mind a little, but it ran very smoothly and I put it to bed.
While I was messing with the v-boost today, I noticed that the #1 coil wire (cop) had the glint of copper. Upon further inspection I found that the wire was backed out. No doubt the wire came out from all the battery swapping, charging, carb/v-boost removal stuff. I have been moving a lot around, and have had the coils in and out numerous times.
Just to verify that I had been riding an incredibly smooth triple, I pulled the spark plug. Sure enough...the plug on the left is from the #1 cylinder:
So, it is all starting to add up. What amazes me is how smooth it runs on 3 cylinders!!! It was a little hard starting, though. :biglaugh: So now I will procure a new coil wire. I might wait until my new intake boots arrive before I put it all back together?
So, in a nutshell, it looks like:
1) V-Boost not opening all the way
2) Only running on 3 cylinders (damaged coil wire)
I don't want to count my chickens before they hatch, but that is my diagnosis for now. The only way to know for sure is to get it back together and on that dyno again.
wildweasel_pt
Well-Known Member
Make sure the problem is on the HT lead and not on the plug socket. Those rear coils have to be properly fitted as the HT lead has to be pushed snug inside the coil and then screw the cap, its not hard for the HT lead not to be properly pushed into place and fouling the electrical connection.
If you still have power problems after solving that, take a look at your vacuum sensor. it may be playing tricks on you as well (just a thought)...
If you still have power problems after solving that, take a look at your vacuum sensor. it may be playing tricks on you as well (just a thought)...
RaWarrior
Well-Known Member
Well, there's your problem!
Since you're running COP's on an 89, you do have the resistors in line, right? If you're running the adapter harnesses they're built in, otherwise I believe it's a 3k resistor. '90 and up bikes have digital ignitions and don't need them, but the 85-89 have analog boxes and they will fry otherwise.
Your a/f curve actually looks pretty good. I want to say mine ran right about 14:1 balls out, and it spun 112hp with slipons and a K&N drop in. I think it was a little stronger after switching to the 147.5 mains (instead of stock 150), but I never dyno'd it again to see.
Give it another pull as a V4 again and I bet you'll definitely be in the ball park.
Since you're running COP's on an 89, you do have the resistors in line, right? If you're running the adapter harnesses they're built in, otherwise I believe it's a 3k resistor. '90 and up bikes have digital ignitions and don't need them, but the 85-89 have analog boxes and they will fry otherwise.
Your a/f curve actually looks pretty good. I want to say mine ran right about 14:1 balls out, and it spun 112hp with slipons and a K&N drop in. I think it was a little stronger after switching to the 147.5 mains (instead of stock 150), but I never dyno'd it again to see.
Give it another pull as a V4 again and I bet you'll definitely be in the ball park.
I think this may be the problem (at least on the coil wire). :biglaugh: I will do some research on the vacuum sensor, I like to know how these things work...
Yes, they have some resistors on the line. On my FI bikes I run closer to 13:1 on the street, and a little fatter than that for top speed racing (with oxygenated race fuel). It doesn't always give the best dyno numbers, but mph at the track is good.
RaWarrior
Well-Known Member
I thought it was a little lean also when I saw the chart, but it ran fine so I didn't want to mess with it. I've had it pinned on the highway for 2-3 minutes at a time, 9000rpm at 145mph on multiple occasions. If she was gonna burn down it would have then. In fact, the water temp barely rose. Maybe 10* above normal, and the motor never missed a beat aside from a lot of popping and snapping from the hot exhaust when I'd finally back off.
Not every bike likes the same a/f ratio. I really don't know enough about this one to say what is best. What I can say is that dyno #'s don't always equate to the way a bike runs on the road or track. Sometimes a leaner ratio will produce a higher dyno number, but give up mph at the track. But as I say, every model can be different. What I look for is mph at the traps...then you know if you are really making the power.
Just snooping around the bike after work. I measured the v-boost valve at approximately 32mm, meaning it is not a 1985 v-boost valve assembly. Although I have never had one in my hands, I read that the 1985 had a 30mm valve assembly.
Work has been kind of busy this week, so not much going on with the bike. Soon I am going to "massage" the v-boost manifolds and try to get them to match up to the head a little better. Then I will replace all of the rubber parts on the assembly. I have some coil wires on order, but I may end up putting the old coils on the rear two cylinders, just to get it running. It depends on my progress with the manifolds.
Work has been kind of busy this week, so not much going on with the bike. Soon I am going to "massage" the v-boost manifolds and try to get them to match up to the head a little better. Then I will replace all of the rubber parts on the assembly. I have some coil wires on order, but I may end up putting the old coils on the rear two cylinders, just to get it running. It depends on my progress with the manifolds.
KJShover
Proud Vmax lover
You are correct, they increased the Vboost size when they had to change the pipes to keep the horsepower the same.
I always thought it would be pretty cool to see the power from a max with the later year's Vboost and ignition with the original, pre neuterd 1985 pipes.
Weighing some parts tonight:
Rider footrest: 8.6 oz
Passenger footrest: 9.6 oz
Turn signal: 9.4 oz
Airbox with K&N filter: 3 lbs 14.7 oz
Rear seat section: 1lb 15.9 oz
Rear shock: 5lbs 10.6 oz
I will be weighing parts as the opportunity presents itself. I happened to have some parts from that old basket case, so I didn't have to take my bike apart for some of these things. Ultimately this information will help me strike a balance between the lightest weight machine that a 10/10th's track bike can be, and the more reasonable street/strip machine that I am creating. I am starting to get a picture in my mind's eye, and I like it! :biglaugh:
Rider footrest: 8.6 oz
Passenger footrest: 9.6 oz
Turn signal: 9.4 oz
Airbox with K&N filter: 3 lbs 14.7 oz
Rear seat section: 1lb 15.9 oz
Rear shock: 5lbs 10.6 oz
I will be weighing parts as the opportunity presents itself. I happened to have some parts from that old basket case, so I didn't have to take my bike apart for some of these things.
Ultimately this information will help me strike a balance between the lightest weight machine that a 10/10th's track bike can be, and the more reasonable street/strip machine that I am creating. I am starting to get a picture in my mind's eye, and I like it! :biglaugh:
