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Thread: The engine rebuild

  1. #1
    Join Date
    Jun 2007
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    Bris Vegas
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    Default The engine rebuild

    I decided to start a new thread for the engine rebuild and conversion to 888. So far I have put in 34mm inlet valves in the 748 drop cam heads. Cleaned up the combustion chambers and inlet ports. Matched the inlet manifolds to the ports. Fitted new bearings to the crank cases.
    7307 2TB x1
    7207 2ETN x1
    6305 C3 x2
    NJ203 ECP C3 x2
    NU202ECP x1
    6004 C3 x1
    Last week I measured the crank for nasties and found it to be perfect except for a 0.015mm wobble at the alternator end, but I'm not going to quibble about that. Journal is 41.998mm. They will be set up with 0.05mm crush, in this case 0.16mm of shim each side. The three bond gasket is given 0.03mm thickness.
    Today I began fitting the monster S4 gearbox US$120 (it's close ratio with a 5mm longer out put shaft that the sprocket sits on). The gear end floats were all with in limits except the 3&4th idle gear on the secondary shaft. The book says a max of 0.25mm and I had 0.65mm. I did try to squeeze in another thrust washer (0.5mm) ,but it bound it up, and as I really didn't want to grind one down (I did start to), I left it as it is. I question Blob and he said it would be Ok the oil has to get in somewhere.
    So far I have set the end floats. Primary is 0.13mm, secondary is 0.15mm, and the clutch drum is 0.27mm. I have also begun setting the selector forks, with the primary being done first. Its a bit tricky, but easy once you have grasped the idea that the dog gears drag the gear into engagement and you can sit there and look at the way it works. I have 0.07mm clearance on both selections between the fork and slot in the gear with the gear home. So I'm happy about that as well. Next week I'll do the secondary shaft.
    This week my other parts should arrive. I'm getting a set of Corrillo rods, and S4/ST4s cams. I was trying to find a set of 996sps cams, but I couldn't be bothered waiting for a cheap set. The second hand cams cost US$120. I believe they will give me the torque increase I want (Thanks Brad) considering the rev range I'll be operating in, and still have enough air going through to get me to 10000 rpm comfortably due to the slightly larger valves.
    In the extras dept I have the Ducati performance lightened flywheel, the smaller alternator rotor and the S4 gear selector mechanism and jockey wheel for the end of the drum. An oil cooler from a monster that cost nothing as its slightly damaged. I'm also eyeballing a radial brake master cylinder, but the set up I have works pretty darn fine, compared to an 848, so I don't now about fitting it.
    All in all I think it will be an alright package. I intend to run it for a couple of years then fit the 900ss crank I think. That should keep me amused for a while.

    Griff
    Last edited by griff851; 11-02-2008 at 07:10 PM.

  2. #2
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    Default

    Griff,
    That should be a "snappy" engine with the high compression and those cams! Are you going to lighten the crank? Might as well as you have to balance it anyway.

  3. #3
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    Jun 2007
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    Default

    Hi Marvin, I'll probably not be lightening the crank anymore than necessary. It is for the road after all, and if it gets too snappy it will just chew through tyres. If that turns out to be the case I'll just stick the old flywheel back on. I was concerned about having to use the steel plates with my MPL clutch, now I tending towards thinking it might be a good thing to get a bit of rotational mass, remembering that handling is effected by removal of rotational mass as well. Lighten the gyros, speed up the turning. If the worst comes to worse I'd have to fit a steering dampener I guess. Last ride I had legs in the air due to a tank slapper at 150kmph in the middle of a corner. Very amusing.
    It's just not easy to find the right balance for use, but at least with bits to swap around I can play.

    Griff
    Last edited by griff851; 10-28-2008 at 06:06 PM.

  4. #4
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    Default

    Griff,
    Remember that your clutch rotates at 1/2 engine rpm so not all that important IMO. I had stock weight crank in my engine with a Nichols flywheel and clutch basket, it wasn't a problem at all.

  5. #5
    Join Date
    Jun 2007
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    100

    Default

    hey this will be a really fanny motor

  6. #6
    Join Date
    Aug 2007
    Location
    Cornwall S.W. England
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    Default

    This all sounds very interesting Griff, please keep the updates coming.
    Can you tell us/me the cam timing figures and lift for the ST4S cams?
    If my memory is correct the ST4S was basically a 996cc motor with the same size valves as the rest of the 996 range but tuned for more torque than the 996 Bip, which (The 996 Bip) had Strada cams the same as fitted to our base model 851/888's and the 748/916's.
    Are the ST4S cams a 1/2 way house between the Strada cams and the 996SPS items?
    Or are they Bip or 996SPS cams that are re-timed for more torque?
    I'm intrigued...

    I'm with you on leaving the crank standard weight for the road.
    Super lightweight cranks tend to be OK if your accelerating hard, or using them on the track, but a pain when trying to ride on a steady throttle and even worse on a bumpy road.
    It's very tempting when you've got the motor apart and tuning it to go for all out power, but full race motors aren't really suitable for everyday use on the public highway.
    Something that I've found out over the years.
    In the past i've built some very hot motors for street use only to feel the need to calm them down a bit afterwards.
    Full race motors on the road are often slower in use in the real world than Tuned for the Road motors.
    It's hard to keep a race motor on the boil, (Keep your licence and stay alive!) by the time you've danced on the gear lever and got her on the cam, the torquey road tuned motor has dissapeared into the next corner and then into the distance on a switch back road.

    Steve R

  7. #7
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    Default

    Hi Steve they are almost the same as standard except the inlet close is at 60 instead of 70. (Thanks Brad).

    http://www.guzzi.com.au/performance//camtime4v.html

    http://www.guzzi.com.au/performance//monsters4diff.html

    Griff

  8. #8
    Join Date
    Nov 2007
    Location
    Eelde, Netherlands, (next door Assen GP circuit)
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    36

    Default

    Nice project.
    I race an 888 here in the Netherlands but cracked up the crankcase last august after 4 years of racing.
    Now I'm also building a new engine using the 900ss crankcases.
    After rebuild it will have the following mods in addition to the mods 4 years ago:
    All 6 interior wheels lightened, lightened crankshaft (done 4 years ago), G cams, lightened flywheel, newly nikasiled cilinders and FBF HC pistons.
    Last 4 years the engine produced 116 BHp and I hope to gain at least another 5 with the open mufflers and tangential exhaust.
    Racing starts again in april 09 so still way to go before the show opens up.
    Last edited by hqracing; 10-31-2008 at 05:56 PM. Reason: grammar
    There are only 3 sports in the world , Mountain climbing, Bull fighting and Motorcycle racing. The rest is just kids play. (Ernest Hemingway)

  9. #9
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    Jun 2007
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    Bris Vegas
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    Default

    Do you have a short throw throttle? An ex TT rider mate I know reckons they are worth another 5 hp on the track. Its a feel thing.

    Griff

    PS Ernest was a hell of a bloke.!
    Last edited by griff851; 10-31-2008 at 06:45 PM.

  10. #10
    loony888 Guest

    Default

    balancing the crank will almost be mandatory i would think griff, mainly due to the light flywheel, i fitted one before bevan did the big rebuild and the vibrations were a bit annoying!! add to that the carillo's which are almost 100gms lighter than the pankl steel rods and if you fit aftermarket pistons as well you may as well say there's another 100gms each ( mine has wiseco and i picked them because they had SOME skirt for long life) and your rotating mass will be lighter by well over a kilo at least!!!!! after dynamic balancing of my assembly it's super smooth with no vibration at all and it's very very light, spins up super quick, especially compared to my S4R.


    paul.

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