Calling Dooman And Any Mxz 700 Pros

[TWINPIPE]

Need a little feedback:

I have Crank Shop trail pipes, head cut to match pipes, and trail porting (all by crank shop), V-Force reeds, bored carbs - 42.5, jet needle 7DHY6 on 4th or 5th clip depending on air density, needle 224-Z9, pilot = stock, main jets 330 / 340, throttle valves stock (2.5), and wiseco pistons.

These mods ran a bit on the lean side below 15 degrees, but were great otherwise. I added KN filters and increased my mains to 360. My first time out with the new filters I melted my clutch-side piston. I am going back to SDoo pistons as I never had trouble with them. How much higher should I be on my main jets? What do you think about the needle jet, jet needle, and pilot? Is it OK to run the KN filters leaving the airbox sensor unplugged?

I have faxed BBickford and Kurt (Crank Shop) as they are familiar with this package but would like to hear from the minds of SMW.

Any info is greatly appreciated SWRules

[hillpounder]

I was up 10 sizes (380's) with pods and pipes (jaws), stock needle and nozzle needle raised 1 clip. DPM working with airbox sensor just zip-tied close to the baro tube on the mpem. I didn't think there was much gain with the pods for the type of riding I did, at least to justify the noise and mpg hit I took, went back to the airbox and 330's. The low port timing on the 700 doesn't really let pipes work as good as they should. Raise the cyls and then they can start to breath.

[TWINPIPE]

Thank You Hillpounder. I am just running this sled on the local ice so don't really need to worry about mpg. Do you mean raising the cylinders with a thicker base gasket?

DOOMAN, THUMB DR. what do you gurus think?

[700speed]

TWINPIPE, I Have a 00' 700 with crankshop twins. I'm running 360 mains, stock needle and clip position. I did however bump up the needle jet to a AA-2. I run a a consistant 1250-1270 WOT. This year I freshened up the topend with a new set of Doo pistons, and have been pleased with them. I thought about Wiseco's cause of there prices, but was happy to see coated pistons from Doo. I also tossed the airbox this year and threw on a set on K'N 's. I too left the temp probe hanging, without a change of jetting. When I called Kurt at CS he told me that they haven't run a trailsled without an airbox, and didn't have any advise as to what DPM and no filters would do to the jetting. I believe the two compensated for themselves.

[TWINPIPE]

SPEED - I would keep an eye on the plugs with the 360 mains. That is what I had when the piston tightened up. Of course I have 42.5 carbs and different n. jet, but I was at 1208 on the EGT and you are quite a bit higher (1250-70). How far on the pipes did you place your probes?

[700speed]

I can't recall as to the specs on the probe placement, I would have to measure it again to tell you exactly. I do know however that it's set right because it's the measurement that CS gave me for the pipes.

As for the 360 mains, I've found them to work real well even when the temps drop to 0 or below. I experimented with various sizes and went as high as 380's, but they were too rich WOT.
You mentioned that you burned down at 1208. I'm no expert but that doesn't seem all that hot. From my understanding they are designed to run 1200 to 1250 WOT for optimum performance. detonation isn't supposed to occur until alittle over the 1300 mark.
You didn't mention at what point the burndown occurred. what throttle position and if these were the stock pistons?

[TWINPIPE]

I spoke with Bill B. and Kurt (CS) today regarding mods for the 7. Both suggested tuning the mid range by getting bigger needle jets. The problem that I have now is knowing the difference between a smaller and larger jet.

Kurt said to get 224 AA3 or AA4 but Bill Bickford said that the 224 Z9 in the carbs right now are bigger than the AA3 / AA4

I have seen a couple older charts and they both indicate the following increments:
Z0 Z2 Z4 Z6 Z7 Z8 Z9 AA0 AA2 AA4 AA6 BB0 BB2 BB5 CC0 CC3 CC5

Anyone confident of the correct increments?

SPEED - the pistons were Wiseco and two dealers said not to run those anymore as they are not as durable or compatible with the DOO cylinders. I was getting off the pin when she got tight. So I agree that the needles need some work.

[hillpounder]

The stock carbs have a z7 nozzle, an z9 would be richer. Simular but not the same as running your needle 2 clips richer (with the z7).


How thick the needle is also plays into it. For example the 700 uses a z7, but the smaller 600 uses a z9. The difference is the needle they use.

The need for bigger jets is mostly caused by the airbox removal, NOT the pipes. I also see guys chasing down high egts in the midrange with huge nozzles, if it make you comfotable go for it, but higher egts is common on stock safe jetted sleds.

[700speed]

TWINPIPE,
The jetting chart that I have lists the needle jets in the same order as you listed. I don't know why Bill would have told you that the Z-9 is larger than a AA3. I would try a AA-2 or 3 and adjust your clips back alittle. The wisceo's I believe are Forged instead of Cast like OEM, So they expand at a faster rate and have tighter skirt clearance. What did Kurt have to say about ideal / max temps to run? I'm curious still as to why you burned down at 1208.
hillpounder,
When I first piped and clutched my sled I settled upon the 360 main jets. That was with the stock airbox. I switched to K/N's just this year, and didn't have to adjust the jetting at all. I'm running the same EGT's I was the year before. Just now i have the Dpm temp sensor hanging. not sure if it really makes a difference or not.

[TWINPIPE]

SPEED - you are right about those WISECOs. You need to make sure you warm up the sled prior to pinning it. The WISECOs also expand faster and if the jetting isn't close to perfect you have a higher potential to melt them due to quicker expansion. I am willing to pay more for SDOO pistons as they seem more forgiving.

As far as BILL's feedback I'm not sure that he gave the question much thought. I looked at some of the SDOO manuals in the jetting sections and found the info to be vague. They have a list of single-lettered jets with numbers and double-lettered jets on the facing page but no specific info on what size is larger. Even the lead technician couldn't tell for sure. I asked KURT (crank shop) about the jets when he returned my call and he confirmed that the double-lettered jets are bigger than single-lettered ones. I also got an old GPI parts book from IRISH that listed them in the same order.

As far as the melting at 1208 - I think that my mains (ranged from 330 - 360) were not large enough; most importantly I think I was running wrong needles - 224 Z9 (4th clip). The sled ran OK WOT but was so lean in the mid that as soon as I got off the piston did to. I should have at least AA2 with the pipes to help the midrange. Because I have 42.5mm carbs and K&N I installed AA4 on the 5th clip and will go out with a buddy over the W/E to get it dialed in. My mains were bumped up to 400. I think this will also load it up but we'll see what happens tomorrow. Kurt suggested AA3 or AA4 with an increase of 6 or 7 sizes on the mains if running filters along with pipes and bored carbs. The egt should be 1200 - 1250.