Page 1 of 2 1 2 LastLast
Results 1 to 10 of 20
  1. #1

    Planning to rebuild and upgrade carbs. Missing anything?

    Hey guys,

    I've got cold and hot start issues with my GP1200r 66v, PV motor. I've been told carbs need to be cleaned / rebuilt which has never been done. The ski now has about 70 hours on it and is 12 years old. It also bogs after a short idle. WHen run hard, it runs great. Spark plugs are reading a bit lean for me after a few minutes run at WOT. In thinking up modification and upgrades, I'm fine with doing a little of both at the same time as doing rebuilds.

    I've done my reasearch and am close to pulling the trigger. Thus far I've got the below 'plans' but am unsure if the list is 'complete' enough for Carbs. I'm hoping I can skip doing anything to reeds or otherwise.

    Current Parts planned for the carbs:
    3ea.- Main Jet, SBN 125
    3ea.- Needle-n-Seat, 1.5, Viton, Super
    3ea.- Pilot Jet, SBN 110
    3ea.- Spring, Needle Valve Arm, 95 Gram
    3ea - Genuine Mikuni rebuild kits
    3ea - Carb base gaskets

    Current Planned Carb modifications
    Remove Choke plates and assm
    Rework Accel Pump to Choke cable (Turning it into Primer only on 1/3 cyl)

    Current Planned Intake modifications
    Modified /drilled stock airbox with airducts removed

    Next season's plan
    Aftermarket F/As
    *150psi head
    *Upgrade carb jets if needed
    Upgraded prop
    Hull re-inforcement

    Current modifications
    Carb High/Low T-Handles
    D-Plate with Chip
    Pump seal kit
    Riva intake grate
    Amsoil Dominator/ Race oil Premix 40:1
    OMP removed
    Waveeater Clips


    DOes it sound like I'm missing anything? The cost for this is about $240 or so.
    Last edited by ZeroClient; 06-19-2013 at 09:52 AM.


  2. #2

    Join Date
    Jan 2006
    Location
    Texas City, Texas
    Posts
    1,249
    +1
    15
    If you modify the jetting specs and keep the stock air box.... even though the air box has been modified.... I do not think you will be happy with the results. The stock air box is restrictive compared to the "free flow" flame arrestors. What I am saying is that you may have to much "signal" or vacume with the stock air box. The guys who did the research on these jetting specs used free flow flame arrestors thinking that larger jets and more air would make their GPR's run better. I am not saying that the stock air box won't work for you with these jetting specs, I just have very serious doubts. On a positive note, if you decide to use the stock air box and it does not work out for you, it will more than likely run rich rather than lean. You should not hurt your engine.

    In for a penny, in for a pound. If you are going to use these jetting specs, I urge you to consider using the free flow flame arrestors that you said that you were going to buy any way.

    The OEM choke in combonation with the accellerator pump always worked well when my GPR was new up till today. While inside of a quiet garage you should be able to squeeze the throttle a few times and literally hear the fuel being dumped (squirted) into 2 of the 3 carburetors. That along with the choke should be more than enough to draw plenty of fuel to get even the most stubborn cold natured engine to run.

    One other part of this is important. Your fuel tank should hold a few pounds of pressure. With fresh gas in your tank, the tank ought to hiss (depressure) when ever you remove the fuel cap. If this is not happening, this could be part of the reason why it is hard to start and runs "cold" for the first few minuntes.

  3. +1 by:


  4. #3
    For the airbox, I was thinking of doing something like this, where I would fit a piece of corrogated filter-grade stainless 'sheet' inside of the box. I'd cut back as much as I can the cover of the airbox - maybe 90% of the box. The stock metal grate would get binned. Another option is to just keep the metal grate and open the airbox as stated, or leave the cover completely off.

    I honestly feel the aftermarket FAs are too expensive ATM...
    Last edited by ZeroClient; 06-20-2013 at 07:38 AM.

  5. #4
    Hey guys,

    if I get a Riva 155psi head in addition to the flame arrestors - what can I expect to change from the starting post setup?

    Thank you

  6. #5
    I placed an order for everything; listed above for the Carbs. I've also dropped a few bills on some PROK arresters and WPS adapters.

    Am I missing anything or will this carb parts be close to right? This is what I ordered:

    -Already have T-Handles
    3ea.- Main Jet, SBN 125
    3ea.- Needle-n-Seat, 1.5, Viton, Super
    3ea.- Pilot Jet, SBN 110
    3ea.- Spring, Needle Valve Arm, 95 Gram
    3ea - Genuine Mikuni Yamaha rebuild kits
    3ea - Carb base gaskets

    Current Planned Carb modifications
    Remove Choke plates and assm
    Rework Accel Pump to Choke cable (Turning it into Primer only on 1&3 cyl)

  7. #6

    Join Date
    Jan 2006
    Location
    Texas City, Texas
    Posts
    1,249
    +1
    15
    Quote Originally Posted by ZeroClient View Post
    I placed an order for everything; listed above for the Carbs. I've also dropped a few bills on some PROK arresters and WPS adapters.

    Am I missing anything or will this carb parts be close to right? This is what I ordered:

    -Already have T-Handles
    3ea.- Main Jet, SBN 125
    3ea.- Needle-n-Seat, 1.5, Viton, Super
    3ea.- Pilot Jet, SBN 110
    3ea.- Spring, Needle Valve Arm, 95 Gram
    3ea - Genuine Mikuni Yamaha rebuild kits
    3ea - Carb base gaskets

    Current Planned Carb modifications
    Remove Choke plates and assm
    Rework Accel Pump to Choke cable (Turning it into Primer only on 1&3 cyl)

    Looks good.

    I would recommend 1 minor mod. Get a (plastic) 1/4 inch barb splicer and put a 100 main jet on one end. Install this barb splicer in your fuel return line at the carbs. This will help to keep your fuel pressure up, especially when you run your fuel tank low with less than fresh fuel. It could help to prevent or minimize the chances of running lean in these conditions.

    This mod is not a must, but if you have a bog on your hole shot and nothing but opening your pilots will make it go away, then this could possibly help.

    As far as adding a 150psi head, you may have to adjust your high and low speed adjustments, but not the jets themselves.

    You really gain nothing from using an aftermarket head vs. a modified stock head. The domes may need to be reshaped, but someone who knows this 66v engine would know to do that. In either case, the modified stocker head is a cheaper play and a better bang for the buck.

    I do not know what your set up is, but if you dial this in correctly, you will need at least a 13/19 to take complete advantage of your mod.... especially if you do the head work.

  8. #7
    Pistonwash's Avatar
    Join Date
    Aug 2005
    Location
    Florida
    Posts
    3,595
    +1
    77
    Quote Originally Posted by salty View Post
    Quote Originally Posted by ZeroClient View Post
    I placed an order for everything; listed above for the Carbs. I've also dropped a few bills on some PROK arresters and WPS adapters.

    Am I missing anything or will this carb parts be close to right? This is what I ordered:

    -Already have T-Handles
    3ea.- Main Jet, SBN 125
    3ea.- Needle-n-Seat, 1.5, Viton, Super
    3ea.- Pilot Jet, SBN 110
    3ea.- Spring, Needle Valve Arm, 95 Gram
    3ea - Genuine Mikuni Yamaha rebuild kits
    3ea - Carb base gaskets

    Current Planned Carb modifications
    Remove Choke plates and assm
    Rework Accel Pump to Choke cable (Turning it into Primer only on 1&3 cyl)

    Looks good.

    I would recommend 1 minor mod. Get a (plastic) 1/4 inch barb splicer and put a 100 main jet on one end. Install this barb splicer in your fuel return line at the carbs. This will help to keep your fuel pressure up, especially when you run your fuel tank low with less than fresh fuel. It could help to prevent or minimize the chances of running lean in these conditions.

    This mod is not a must, but if you have a bog on your hole shot and nothing but opening your pilots will make it go away, then this could possibly help.

    As far as adding a 150psi head, you may have to adjust your high and low speed adjustments, but not the jets themselves.

    You really gain nothing from using an aftermarket head vs. a modified stock head. The domes may need to be reshaped, but someone who knows this 66v engine would know to do that. In either case, the modified stocker head is a cheaper play and a better bang for the buck.

    I do not know what your set up is, but if you dial this in correctly, you will need at least a 13/19 to take complete advantage of your mod.... especially if you do the head work.
    Salty..you tha man! Great advice...and Zero, the Proks work fantastic, follow Salty's advice to the tee, you will get this ski humpin'! You might even get WFO or one of the Texas gang to recommend a good machinist to mill the OEM head. Nothing wrong with the OEM head, as a matter of fact they cool as good as any aftermarket imo.

  9. #8
    elmatta's Avatar
    Join Date
    Sep 2011
    Location
    CT
    Posts
    311
    +1
    8
    Quote Originally Posted by salty View Post

    I would recommend 1 minor mod.

    This mod is not a must

    http://www.greenhulk.net/forums/showthread.php?t=70129

    http://www.greenhulk.net/forums/showthread.php?t=177671

    All the above mods have been tried, proven and explained by osidebill. They are some of the great mods that he left behind. I would say they are huge and a must.

  10. #9
    I should have added the 1/4 barb and 95~100 jet to the list above. I am planning to do this and am hoping to pull a stock jet out of the carbs this weekend to meet this plan. Only difference is I'm going to find something better than a plastic barb - some kind of brass or metal instead. I believe my local Ace Hardware or PepBoys will have something better than plastic.

    Check on the prop. I currently have a stocker and am planning to go aftermarket when everything gets in-order. Not sure if a 13/19 will meet my needs with 150psi heads, free-flow exhaust tube, & ~8000 rev limit. Most of which will come into play either later this summer or into the new season. I do see a new prob this summer though. Can the Solas Concord 13/19 spin 8000 with good results in the low/mid 70s? What hull speed would that be?

    Thank you

  11. #10

    Join Date
    Jun 2012
    Location
    Pasadena, MD
    Posts
    73
    I plan on doing the same mods on my XL1200 Limited with the exception of leaving the chokes intact. So according to the recipe I would use 120 main jets and everything else remains the same. The ¼ inch barb you are talking about is that the one in Bill’s thread where you can screw the jet into it? If so, I found that at Atlantic jet sports part number RY 12-RLR-14 for $17.50. Now for the stupid question you are using “SBN” in reference to the high and low jets, is this a brand name, a certain type of jet or a reference to the carb? Bill’s posts does not mention “SBN” I am ordering parts in the next day or so and want to make sure I have it right. Thanks.
     110 Pilot jets, 1 turn out on low speed adjusters
     120 main jets, 1-1/2 turn out on high speed adjusters
     1.5 Needle and Seat, 95 gram spring (Dull Silver) 42-45 avg. pop-off pressure.

Page 1 of 2 1 2 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. best place to rebuild and modify turbo?
    By toxicgun in forum 4-Tec Performance
    Replies: 6
    Last Post: 01-16-2015, 02:45 PM
  2. ALmost finished - 2001 GP1200r partial rebuild and upgrade
    By ZeroClient in forum Yamaha PWC Performance (2-stroke)
    Replies: 23
    Last Post: 08-02-2013, 11:10 PM
  3. 2003 virage rebuild and sl750 carb issues-all in one
    By bighad in forum Polaris How To & FAQs
    Replies: 2
    Last Post: 06-03-2012, 10:52 PM
  4. Would I be crazy if I tried to rebuild and install my motor by myself???
    By espritonsevas in forum Yamaha PWC Performance (2-stroke)
    Replies: 12
    Last Post: 04-13-2009, 08:40 PM
  5. Instructions w pics to removing and cleaning carbs?
    By kaarona1 in forum Yamaha PWC Performance (2-stroke)
    Replies: 11
    Last Post: 01-30-2009, 01:17 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •