Machined (modified) stock jet needles

[Akatora]

Hello,

It was difficult to find strong and smooth power band combined with satisfactory top end power using stock needles. On the other hand, Dynojet Stage 7 would have cost about 260 euros and there was plenty of stuff that was actually not needed.

So the profile of the original needles had to be changed... I compared different profiles using other model needles and referred also to the V-Max Stage 7 and Factory Pro needle profiles. Had also to keep in mind the manufacturing point of view...

Ended up to take the needles to the local goldsmith shop to have it done for practical reasons. But the guy needed the instructions, and they were:

- There is a point where the straight part turns into small tapered angle around half way of the needle, let's call it POINT 1
- When we continue to follow this angle down towards the narrow end, there will be another, sharper angle near the end (maybe 10mm apart), let's call it POINT 2
- Then there is a point at almost the end of the needle, which is the end of this angle line, let's call it POINT 3
- And finally, the actual top part of the narrow end, let's call it POINT 4 (height difference from POINT 3 about 1mm)

We don't touch to POINT 4, it will be used as is, and will support the narrow end during the machining work. Instead, we start at POINT 3. The machining work will continue from POINT 3 straight upwards for next 6 mm. The diameter is kept unchanged for this 6 mm and we use the same diameter as is in POINT 3. After made the 6 mm, stop. Then making one angle to continue from this point directly to POINT 1 (this means that POINT 2 will be machined away).

The result is good (near sea level) combined with Keihin 160 main jet and the self made air filter (see http://www.vmaxforum.net/showthread.php?t=4757).

Regards,

AT

 

[4gasem]

Well if that doesn't make you deserve a Mod Monkey award and I don't know what will...

Lets see pics though M8!

 

[one2dmax]

Not too bad a mod but you've richened up your mixture and not leaned it out. If you get a chance you should take the bike in and get it dyno-ed on a machine that has A/F ratio capability. Once you get the intake velocity increased enough you will need correctors to get the carbs to run correctly.

We have made as much HP with stock needles, better fuel economy, and better midrange/lowend then pretty much ANY other kit out there. We've tested FP needles as well as the stage 1 and 7 stuff. All of them richen up the mixture. It can be corrected but most of the time requires a much smaller main.

What you are doing is great but it would be nice to see some validation to your work. The filter mod is very similar to what we have been doing for years for bikes that don't sell K&N filters for. Most of the time that foam doesn't last too long before it starts to break down. It won't generally hurt the carbs but it can make a mess.

Sean Morley

 

[Akatora]

Thanks for the Monkey Award, guys, much appreciate it!

For the mixture set up, I wanted to richen it up a little due to need of recatching the balance after modifying the filter opening.

This was based on the high speed testing, during which I ran jets between 152.5 (original) and 170, with different kind of air filter and jet needle arrangements. With original set up (or original with opened air box intake) it worked ok at lower speeds, but after 125 mph the pull was not too strong anymore. Again, with 170 it was definitely too rich. But with the current arrangement, the pull is very strong even after 135 mph. I'm not claiming it to be the best possible, but it is probably very near. There are several cases set up at dyno which had 155 mains here and they did have stock filters.

There is also interesting article at South African forum, where a guy has similar experience about jetting. See http://www.awol.co.za/AirboxAirfilterExhaust.htm

Here (Finland) it is rather cool air with low humidity and I'm almost at sea level, so the needed set up is a little bit richer than in most cases around the world.

As said, the purpose of the filter arrangement was not to get huge power gains, but to get it run nicely and maybe save some money with maintenance. It's no special, but as compared the restriction with separate Uni Filters which I've also got there, decided to respect Yamaha's original air box which is actually not so bad.

For serious HP quest, I've got there a turbo charger waiting for to be installed. Didn't finally decide yet whether actually do it or not, as there would be some legal paperwork to complete first, but let's see later...


Regards,

AT

 

[one2dmax]

Turbo's bring a whole different level to the playing field. Do a search for the Muscle Jet kit and you'll see what we have been doing based on a lot of dyno, road, and track experience. We keep the lower section of the airbox intact and use a large panel filter in the lid (as well as some other misc stuff).

Sean

 

[Akatora]

Thanks Sean, but I've already found my set-up now.

Additional power available(?) with filters, exhausts etc. is virtually "peanuts" for the effort and cost. If I do anything more, it will be the turbo assembly - and it is now under consideration. If I do it, I do it in the winter.

Regards,

AT

 

[one2dmax]

I understand the winter time off. many wait until spring then want a lot of work done and it's a bit hard to get everyone ready at the same time. We have a person here I have been asking to make some turbo kits for me to sell and he isn't real excited about doing one just yet. I'm not sure what the power level he is making but he ran a best of 9.44 (that I saw - he claims he's been faster) with a 1260 cc chain drive engine with the turbo on low setting. That was with a slick and extended swingarm but no bar.

have fun..
Sean

 

[lankeeyankee]

I like his ideas (well most the gauge thing wasnt my style) and the low cost factor. He would be a great help if I was low on funds and wanted a lil extra out of my bike. Sean, I dont know why you are being hard on the guy?:confused2: His ideas are very cheap. He is not trying to sell them, nor trying to set the new HP record on a jet kit, he is offering advice to those that would like an extra few HP gain at a very little cost.

 

[one2dmax]

He's probably losing power and economy with the direction he is going. Cheap or not that isn't my idea of a good mod. I like his thinking but he's going to get a few bumps and bruises as well as a few at-a-boys while he is experimenting.

Most don't have a machine shop to mod thier needles and if they had to pay to get it done it would cost more then buying them.

Sean

 

[Akatora]

Hello,

For your information, I can assure that the bike is much stronger now especially at high speeds. For another, printed reference, there is a dyno sheet from a guy at vmaxclubfinland's page where he has a complete stock 1997 Max with only 155 main jets doing 123,13 RWHP.

Now mine has modified air intake and therefore having a little bit bigger mains is by no means strange thing! What works fine here might not work in your case, though. I'm not trying to convince anybody to do the same mods, I'm just reporting mine. Let's be happy if we can manage to get our machines to run fine!

And you know what, we automotive engineers often like to do experiments... That's part of the fun among riding these things.

I have no interest to put the bike on the dyno before possible turbo assembly (nearest one is quite far), as the power increases are otherwise so small in any case - we are talking about few ponies after all.

Regarding the fuel economy, this machine is able to do 100-125 miles before fuel light comes on (in the easy highway cruise). Not to mention that the fuel economy is not my main target with the Max.

Regards,

AT

 

[one2dmax]

That may be true, but when you can get 120+ and still get 40+ mpg is when you have it tuned in good. I got 127rwhp and 44mpg with my setup.

Sean