Page 1 of 2 12 LastLast
Results 1 to 15 of 21

Thread: RGV250 Race bike jetting

  1. #1
    Join Date
    13th January 2009 - 21:51
    Bike
    Honda
    Location
    Palmy
    Posts
    127

    RGV250 Race bike jetting

    Ok, only want to hear from people with actual experience in tuning a race spec RGV.
    Bikes running no filter or lid and and I've richened up the jetting but can't get rid of a splutter at 8000rpm when you roll on the throttle from closed position.

    Plugs look good - nice and dry and coffee colour.

    Interested in knowing if anyone knows approx what jetting to be running at Manfeild?
    2 Strokes Rule!
    www.cityhonda.co.nz

  2. #2
    Join Date
    27th May 2004 - 12:00
    Bike
    RSVR-BICILINDRICO
    Location
    V2- PROJECTILE
    Posts
    2,788
    Could be wrong here but I would say the fact the bike doesn't have a filter or lid would be a good reson why its not running well apart from this been bad for the motor not having anyway of filtering the air going straight into the motor . Is there a reson you have taken them out ??

    SENSEI PERFORMANCE TUNING

    " QUICKER THAN YOU SLOWER THAN ME "

  3. #3
    Join Date
    17th February 2005 - 11:36
    Bike
    Bikes!
    Location
    Christchurch
    Posts
    9,651
    Which model? Which carbs? What solenoid plumbing? www.rgv250.co.uk is a better bet.

  4. #4
    Join Date
    13th January 2009 - 21:51
    Bike
    Honda
    Location
    Palmy
    Posts
    127
    Quote Originally Posted by Sensei View Post
    Could be wrong here but I would say the fact the bike doesn't have a filter or lid would be a good reson why its not running well apart from this been bad for the motor not having anyway of filtering the air going straight into the motor . Is there a reson you have taken them out ??


    Ok, only want to hear from people with actual experience in tuning a race spec RGV.


    its set up to get every available HP out of the motor
    2 Strokes Rule!
    www.cityhonda.co.nz

  5. #5
    Join Date
    26th April 2006 - 12:52
    Bike
    Several
    Location
    Hutt Valley
    Posts
    5,120
    Quote Originally Posted by 7mmWSM View Post
    Ok, only want to hear from people with actual experience in tuning a race spec RGV.
    You can say it but yopu aren't likely to be that lucky!

    tried rgv250.co.uk or similar?

    Would a flat spot there affect you in a racing situation?

    EDIT: haha, I was too slow!
    Heinz Varieties

  6. #6
    Join Date
    13th January 2009 - 21:51
    Bike
    Honda
    Location
    Palmy
    Posts
    127
    Quote Originally Posted by koba View Post
    You can say it but yopu aren't likely to be that lucky!

    tried rgv250.co.uk or similar?

    Would a flat spot there affect you in a racing situation?

    EDIT: haha, I was too slow!
    Well I thought I might get lucky as i'm kinda running out of time till the weekend.
    it could affect getting on the gas mid corner.
    I got the kit manual off that site but recommended jetting they list is way too rich i've found
    2 Strokes Rule!
    www.cityhonda.co.nz

  7. #7
    Join Date
    20th September 2008 - 12:50
    Bike
    XT660r
    Location
    Hastings
    Posts
    1,624
    Quote Originally Posted by 7mmWSM View Post
    Well I thought I might get lucky as i'm kinda running out of time till the weekend.
    it could affect getting on the gas mid corner.
    I got the kit manual off that site but recommended jetting they list is way too rich i've found
    What model rgv and what carbs , 32mm or 34mm

  8. #8
    Join Date
    10th September 2008 - 22:00
    Bike
    Smokers and a tractor
    Location
    Wanganui
    Posts
    969
    Don't discount Senseis' suggestion out of hand just yet coz RGV's (or any engine in fact)don't like sucking in heated air flowing in from engine/radiator and by removing the airbox lid you are encouraging this...especially bad with the RGV too.Some have even raised the tank to encourage cooler air in.
    Shrouding of some sort can help here.

    I'm running Tyga pipes,standard airbox,34mm carbs and std mains.Also should mention i'm getting out dragged by 2 fookn NSR's so would be keen on seeing how your mods are working this weekend.But not to keen,if ya know what i mean haha.

    But when it starts bogging/spluttering does rolling off of the throttle slightly improve fueling?
    You say just as you are rolling on the throttle so i'm presuming up to 1/4 opening which basically means you should be looking at the air jets and possibly needles.

  9. #9
    Join Date
    13th January 2009 - 21:51
    Bike
    Honda
    Location
    Palmy
    Posts
    127
    Quote Originally Posted by RDjase View Post
    What model rgv and what carbs , 32mm or 34mm
    34mm carbs
    2 Strokes Rule!
    www.cityhonda.co.nz

  10. #10
    Join Date
    13th January 2009 - 21:51
    Bike
    Honda
    Location
    Palmy
    Posts
    127
    Quote Originally Posted by eelracing View Post
    Don't discount Senseis' suggestion out of hand just yet coz RGV's (or any engine in fact)don't like sucking in heated air flowing in from engine/radiator and by removing the airbox lid you are encouraging this...especially bad with the RGV too.Some have even raised the tank to encourage cooler air in.
    Shrouding of some sort can help here.

    I'm running Tyga pipes,standard airbox,34mm carbs and std mains.Also should mention i'm getting out dragged by 2 fookn NSR's so would be keen on seeing how your mods are working this weekend.But not to keen,if ya know what i mean haha.

    But when it starts bogging/spluttering does rolling off of the throttle slightly improve fueling?
    You say just as you are rolling on the throttle so i'm presuming up to 1/4 opening which basically means you should be looking at the air jets and possibly needles.
    Yes we will find out this weekend!

    Current jetting is

    360/370 mains
    27.5 Pilot
    #55 needle in 2nd position
    0-9 needle jet
    0.7 PAJ
    0.5 MAJ



    I will try dropping the Needle jet down to 0-8 and I think I have spare 0.5 PAJ that I will try.

    My Airbox has been modified to draw in cooler air with a heat sheild between it and the motor.
    2 Strokes Rule!
    www.cityhonda.co.nz

  11. #11
    Join Date
    5th February 2008 - 13:07
    Bike
    2006 Hyosung GT650R
    Location
    BOP
    Posts
    7,141
    I have a couple of 2T pocketbike race engines (18k redline), and that mid-range falter usually means it is set a tad too lean. One of my bikes has an adjustable main jet, and a verrry slight tweak towards rich should clear it up.

    Unloaded, from idle, if you full-throttle blap it, does it instantly rev hard and cleanly or does it slightly falter? If it falters every so slightly, then richen just the smallest amount.

    Steve
    "I am a licenced motorcycle instructor, I agree with dangerousbastard, no point in repeating what he said."
    "read what Steve says. He's right."
    "What Steve said pretty much summed it up."
    "I did axactly as you said and it worked...!!"
    "Wow, Great advise there DB."
    WTB: Hyosung bikes or going or not.

  12. #12
    Join Date
    18th October 2007 - 08:20
    Bike
    1970 Vespa ss90
    Location
    Schärding
    Posts
    1,831
    Quote Originally Posted by 7mmWSM View Post
    Yes we will find out this weekend!

    Current jetting is

    360/370 mains
    27.5 Pilot
    #55 needle in 2nd position
    0-9 needle jet
    0.7 PAJ
    0.5 MAJ



    I will try dropping the Needle jet down to 0-8 and I think I have spare 0.5 PAJ that I will try.

    My Airbox has been modified to draw in cooler air with a heat sheild between it and the motor.
    It's unlikely that anyone will give you magic numbers on the net, but as a matter of interest, you say "set up to get maximum power from the engine" that's a risky statement.

    What sort of expansion chambers do you have?

    It's an important question.

  13. #13
    Join Date
    9th July 2004 - 12:34
    Bike
    KTM300EXC
    Location
    Porirua
    Posts
    493
    I raced a RGV for a number of years and played with lots of settings. In the end I went for 5hp less than max to go for reliability (good tyres and suspension counts for lots!) meaning I ended up back with a thin filter and the air box lid for example, 30:1 and slighty dark plugs etc etc. I did cut out big holes though in the lid for a bit more breathing, and also had a heat sheild.

    Regarding jetting, I agree with some responses, you won't get majic numbers on the net - each bike seems to be a little bit different, and also humidity and air pressure affects it all to. you need to sort jetting out in the real world in the end. I did settle on a main jet and pilot though for Taupo/Pukekohe/Manfeild and just moved clip positions so will see if I can find those out for a baseline if it is any use. I had a full arrows exhaust, plus a port and polish with lightened crank, so a fairly tuned engine.

    Hesitation at 8000 rpm might not be jetting though if the plugs are a nice colour - the ignition on my bike did some wierd things cuasing random rpm blips, only sometimes. It drove me nuts trying to find it, in the end I systematicall replaced the whole ignition in turn - and it was the picks up causing the issue. I got a new set of them and viola - SV650 beater was back (in the corners anyway)

  14. #14
    Join Date
    4th March 2008 - 09:18
    Bike
    big and ugly
    Location
    Invercargil
    Posts
    47
    Quote Originally Posted by That Guy View Post
    I raced a RGV for a number of years and played with lots of settings. In the end I went for 5hp less than max to go for reliability (good tyres and suspension counts for lots!) meaning I ended up back with a thin filter and the air box lid for example, 30:1 and slighty dark plugs etc etc. I did cut out big holes though in the lid for a bit more breathing, and also had a heat sheild.

    Regarding jetting, I agree with some responses, you won't get majic numbers on the net - each bike seems to be a little bit different, and also humidity and air pressure affects it all to. you need to sort jetting out in the real world in the end. I did settle on a main jet and pilot though for Taupo/Pukekohe/Manfeild and just moved clip positions so will see if I can find those out for a baseline if it is any use. I had a full arrows exhaust, plus a port and polish with lightened crank, so a fairly tuned engine.

    Hesitation at 8000 rpm might not be jetting though if the plugs are a nice colour - the ignition on my bike did some wierd things cuasing random rpm blips, only sometimes. It drove me nuts trying to find it, in the end I systematicall replaced the whole ignition in turn - and it was the picks up causing the issue. I got a new set of them and viola - SV650 beater was back (in the corners anyway)

    I just spoke to one of my mates that used to race one and work on them about your post. 'that guy' = great post. As he mentioned, the internet jets are a just good starting point for similar mods. The needle is absolutely key (clip position).
    With regards to the airbox, my mate said that best reliable power was made with just slightly enlarged inlet holes (from 32mm to 34mm-tho some go to 36mm). Open airbox=big power=less reliability=big bang.

    He also said that rgvs powervalves open 500rpm too early and give a dip in power curve around 8000rpm(on tacho). The best solution is to get an aftermarket unit and make the PV's open 500rpm later. Manual adjustment of PV does not work. His last word of advice was that best results are obtained with only a slightly modified engine with well sorted suspension ans tyres (as 'that guy mentioned also).

    Jetting is based on throttle position-not revs (if its always at certain revs, then the issue is elsewhere. Put tape round the throttle and label positions (1/8, 1/4, 1/2) then use these to help with jetting. A good tip

    Take it or leave it, but I usually take his advice and have only good results

  15. #15
    Join Date
    13th January 2009 - 21:51
    Bike
    Honda
    Location
    Palmy
    Posts
    127
    Quote Originally Posted by blackstars_10 View Post
    I just spoke to one of my mates that used to race one and work on them about your post. 'that guy' = great post. As he mentioned, the internet jets are a just good starting point for similar mods. The needle is absolutely key (clip position).
    With regards to the airbox, my mate said that best reliable power was made with just slightly enlarged inlet holes (from 32mm to 34mm-tho some go to 36mm). Open airbox=big power=less reliability=big bang.

    He also said that rgvs powervalves open 500rpm too early and give a dip in power curve around 8000rpm(on tacho). The best solution is to get an aftermarket unit and make the PV's open 500rpm later. Manual adjustment of PV does not work. His last word of advice was that best results are obtained with only a slightly modified engine with well sorted suspension ans tyres (as 'that guy mentioned also).

    Jetting is based on throttle position-not revs (if its always at certain revs, then the issue is elsewhere. Put tape round the throttle and label positions (1/8, 1/4, 1/2) then use these to help with jetting. A good tip

    Take it or leave it, but I usually take his advice and have only good results
    Thanks for that, My biggest issue at the moment is probably more lack of test time on the track. Only time will tell but it would've been nice to have it nearly sorted in time for the weekend
    2 Strokes Rule!
    www.cityhonda.co.nz

Thread Information

Users Browsing this Thread

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

Posting Permissions

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