07 TTR230 & WFR 450 Modifications - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 08-02-2007, 07:23 AM Thread Starter
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Thumbs up 07 TTR230 & WFR 450 Modifications

I own two 07 TTR230's and an 07 WFR450. I have followed Ricks advice by changing the front sprockets from a 13 to a 14 on the 230's, and from a 13 to a 15 on the 450, (I tried a 12, 13, 14, 15 & 16T on the 450, and a 12, 13, 14 & 15T on the 230, with the best results as a 14T on the 230 and a 15T front sprocket on the 450). The rear sprockets are still the standard tooth count.
The Xhaust spark arrestors were removed from all of the bikes, (a hacksaw being necessary on the 230's ) ... and ... these bikes have been literally transformed!

The next step(s) are to remove all the airbox trumpets under the seat, along with the "fly screens" and re-jet. I wondered if anyone had any ideas on jetting sizes for both the 230 and 450? also;

How great, (or not?) is the TTR 230 head? Would it benefit from a lil' porting, (or just mild polishing), (I've heard that they desperatly require removal of "dingleberries"), and/or an inlet valve size increase? also;

The local agent suggested removing one of the head gaskets? ... Is there more than one? and;

Are there any better cams and/or pistons available for the 230's?

Finally ... What is so great about all these aftermarket headers / pipes? and which one/s actually work? ... as against just making the bike sound faster by being louder!
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post #2 of (permalink) Old 08-13-2007, 06:01 PM
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I would pull out the snorkel & screen, cut the snorkel hole larger (see photo), and install a 130 main jet. I have not looked at my head yet, but if I do not sell the bike this year, I plan on porting it soon. I installed the Big Gun exhaust system, and not only does it add gobs of power, the bike is quieter than it was with the modified stock exhaust, and it sounds better as well- was worth every penny. I have not looked into cams or big bore kits recently, but as of last year, they were still unavailable.
post #3 of (permalink) Old 08-14-2007, 01:45 AM Thread Starter
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Wink Thanks max ...

Thanks max ...

I've done something similar , (and also removed the "flyscreen") , however, as we tend to cross rivers fairly often, rather than cut open the side of the airbox as most people do ... and risk drowning the motor ... I cut another opening on the top of the airbox and fitted a second "trumpet", (both of which have been shortened slightly)

To date I have also "gutted" the silencer, and after sourcing a piece of pipe the same dia as the headers, and drilled a combination of 1, 2 and 3 mm holes through most of the length, welded that into the silencer cavity, surrounding it with fiberglass wool, and used the original "end cap" with a larger opening to accomodate the new pipe.
It's much the same "loudness" as just removing the baffle/spark arrestor, however they now have a lot more mid range as well as top end power

What else ....
I've rejetted the bikes, and I've ported them ever so slightly, (the stock heads are VERY really poorly cast !), and I've profiled the rockers, (retarding the inlet and advancing the exhaust) , as cams don't seem to be available , and this achieves much the same, also;

I raised the compression ratio slightly, by removing the "centre" of the head gasket , "replacing" it with gasket sealer, (yes, I re-used the old gasket as well ... It's an old trick we used in Formula Ford )
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post #4 of (permalink) Old 08-14-2007, 05:53 PM
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That's some good info; nice to hear that you can play with the valve timing and head gasket without clearance issues. Just to get this straight: by advancing the exhaust and retarding the intake cams, do you mean you moved the top of each cam gear one tooth closer to center? Or do I have that backward?
post #5 of (permalink) Old 08-15-2007, 01:31 AM Thread Starter
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Wink Cam Timing

I wouldn't be as enthusiastic as to change the timing by a full tooth! ... as this affects both inlet AND exhaust timing in the same direction!

I did it by profiling the rocker face, (where it contacts the cam) . I used a dial guage on a loosely tightened head to check cam phasing, (before and after), and a small blob of plasticine on top of the piston to check piston to head and valve to piston clearances . I had a degree wheel, (fabricated from a 360 deg. protractor attached to the flywheel)

Check out the link ; https://forums.off-road.com/dirtbike-...sprockets.html

As the 230's have a cam with constant lobe centers and cam duration, advancing the cam in its entirety, (between 1 and 6 degrees MAX!), would improve low and medium rpm torque , with a SLIGHT reduction in peak power, (with imperceptible changes in emissions, idle and fuel consumption, ie. no change in jetting required). (I wouldn't recommend exceeding 6 degrees!)
Retarding the cam in it's entirety on the other hand moves the intake / exhaust timing events to a point later in the TDC of the ascending piston, which shifts torque from lower rpm to a higher-speed range. Overall, the advance/retard scheme creates a torque shift.

Profiling on the other hand can be done to a single lobe / single valve , ie. either the inlet or exhaust or .... both as I have done ... as retarding the intake and advancing the exhaust, spreading the centers, decreases overlap and results in a wider power band

Bearing in mind that TORQUE, (the twisting power of a motor), is the increase that you're after , and that even in racing, the name of the game is acceleration , (ie. a wide torgue band from the mid to top end range) ... so you may also want to experiment with intake diameter and length as well?

My current testing shows and increase of bottom end torque, again with a slight reduction in top end by extending the intake length, (clearly the converse also applies).

I can tell you that after all my modifications ... I have a slight, (some 5% ), top end power increase ... however, I have a substantual bottom and mid range boost , (of which I put this to good use with a sprocket change from a 13T front to a 15T) ... to the extent that the 230's now almost feel like the WR450 did when it was new, (with it's 1/2 throttle and other crappy restrictions), except the 230's are considerably lighter and more manouverable!

Before embarking on any modifications however, I would advise thinking them through, (unless you're like me and just want to experiment?) . Decide on exactly what it is that you want to achieve, and what the cost is, (financial as well as a trade of of bottom end to give top end, noise, etc.)

and have fun ...

Last edited by Anthony; 08-15-2007 at 01:56 AM. Reason: typo
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post #6 of (permalink) Old 08-15-2007, 11:33 AM Thread Starter
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Thumbs up The effects / affects of changes in Cam Timing and Lobe Separation Angle

Please don't email / PM me directly ... rather post your request here so we can all benefit ... nonetheless, and as requested, herewith more info on cam timing ;

The attached pic's / tables illustrate how variations in lobe separation angle, (ie. retarding the intake and advancing the exhaust by virtue of profiling the rockers), as well as how overall cam timing effects the behavior of the engine in which the modifications are done.
Attached Images
File Type: jpg camA.JPG (29.7 KB, 0 views)
File Type: jpg camB.JPG (55.9 KB, 0 views)
File Type: jpg camC.JPG (36.9 KB, 0 views)
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