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New engine. Is this normal?

Discussion in 'Technical and Troubleshooting Torque' started by Sweeris, Jul 28, 2007.

  1. I have got a new engine for my bike today. After riding out of the mechanic I found it was completely different to my old engine. I get more torque at lower revs but at higher revs it seem to be less than my old engine.

    Unfortunaly I found something stange about it. In first gear and sometimes in second gear at 8000rpm the engine seems like its not getting enough fuel. In first gear most of the time when I hit 8000rpm it just stop accelerating and I have to put on more throtle to get it accelerating again but after 9500rmp its fine again and accelerates like my old one. I am not sure if its normal or is there something wrong.

    The carby is different than my old one. They said that its abit narrower so I get more torque at lower revs. I did get this but im not sure if it effected my engine like I described. Also the differance is the old engine had racing plugs in them(iridium plug) the new one had standard plugs put in.

    Other than this small problem the engine is quite good. I just realized what I was missing with my old engine.

    Any ideas on what might be going on?

  2. carb issue

    take it back and tell them you have a huge flat spot at 8K and the top end is not as good
  3. Likely a jetting issue, if the old carb was replaced with something (probably the carbs that were on the new motor) else, then the jetting may well be different.

    Were the carbs serviced prior to the new engine being fitted?

    I assume when you say new engine, you mean used engine from another bike?
  4. The engine was from another bike but that bike had only about 8000Km on it.

    As for the carb its the one that came with the engine.

    I expected to be something with the carbs. So they didnt tune the carb properly?
  5. they should have stripped , cleaned and checked the carbs before they fitted the engine,

    but by the sounds of it they didnt

    they should sort this out at no cost
  6. I would be quite pissed if they would charge me for sorting this out. I didnt think they checked the carbs.
  7. Personally I think you're a fool for not getting the old engine fixed, seeing as you had a much cheaper solution available to you. Were you that desperate to spend the money?
  8. Is the engine out of a R or RR. I think the R is down on power compared to the RR. Any CBR people out there that can confirm that?
  9. You don't know how much negotiating went into the install price, maybe it was a budget job? Engine replacements usually are...
    Anyway, I'd just ask them nicely to put the carbs from your old bike onto the new engine, I'd have done that if I was swapping the engine, at least you have known good carburetion then.

    Regards, Andrew.
  10. same engine... the difference lies in it's pickups... only which have to be changed to run in RR (MC22) any way... but they used the carbs out of the R (MC19)?? They should not even fit with the air box!! and from memory* the MC19 uses #90 and #92 jets while the MC22 uses #110 and #120!! so even if they do fit with the air box than they should have changed the jets accordingly....

    *re jet sizes... I'm realy going here off my memory and I think the pilot jets should also be looked at...
  11. By the time I contacted pete the people who I took it to already have dimantaled my bike... :( so I would be spending at least the labour for disassembling my bike and thats about 3hrs. I know of the alternatives but it kinda came up abit late. I'll be ending up spending quite abit anyway. Thanks for trying to help out anyways.

    Other than that the old one seems very loose compaired to the newer one.
  12. So you're saying the base timing is altered to turn an R into an RR just by using different pickup coils?( I also assume different carbs or jetting?) If so, what a rort, detune the R and sell the RR for more!

    Regards, Andrew.
  13. After my ride this arvo the carby seem to have cleared up. Theres no more flat spot. The top end still doesnt seem to run as well as I expected. I'll get it sorted on monday.
    Thanks for all the help.
  14. maybe try some carb cleaner (nulon)
  15. if you got the post 91 (i think???) engine it makes about 5 ponies less to comply with japanese novice restrictions that were brought in around the time. but maybe that was just the ignition unit? i guess the carbies would have to have been retuned aswell.

  16. I wouldn't automatically expect a carb reco with an engine change. A quick tune would be ok assuming that your original carbs were used.

    Remember you get what you pay for and if you haven't paid for a carb reco, dont expect it to be thrown in for free. Do however take it back, also ask for all your original parts, If they are reluctant to hand them back then be suspicious.
  17. With a grey import I'd be assuming the carb jetting was completely wrong. Chances are the engine swap was done on the cheap and a re-jetting wasn't allowed for.

    You said the carbs were "narrower". Do you mean they were of smaller diameter?

    If that was the case I'd be hunting down the old one, but you'd still be looking at a significant retune to match the new engine.
  18. why did you need to get a new motor anyway... what did you do to the old motor? :?