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Pros/Cons of Head Porting 4-strokes

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I'm considering holding off buying a more high-performance bike for now (although eventually I will) and try to have some additional mods made to my '06 TTR230. I've already done the following:

1- Uncorking. Increased air/fuel flow via removing baffle, opening airbox, and rejetting to match with fuel. The results were pretty impressive.

2 - Gearing. 'Went up a tooth from a 13t to a 14t countersprocket. I got the idea from a CRF230 project on offroad.com hosted by Rick Sieman ("old school" guy, hillarious and very informative, check him out!). Much like with the CRF, the gearing was so low - especially for 1st - that the 14t c/s gearing made better use of the power. I'd swear it actually accelerates harder; of course, speed increases and 1st/2nd gears are much more useable. Overall, results were impressive.

I've contacted some places that offer engine performance mods and have learned that several places will perform services stretching from flywheel weight reduction to head porting to all-out overbore jobs. After considering what's available, I'm under the impression that head porting's the way to go: I don't want the stalling from a lighter flywheel weight, I'm not ready to tear down my engine quite yet to get the crank trimmed down (although a more aggressive cam might be reasonable), and I don't want to spend a fortune (I will eventually go for a performance bike in the future).

Any feedback on the pros/cons of head porting? PRC - Precision Racing Components - offers head porting and claims they "do not port in stages, each and every head is ported to maximim PRC race specs." Their prices are very competitive. I contacted them and, indeed, they provide the services for the TTR230 (as do other outfits).

What exactly is done when porting a 4-stroke - same as a 2-stroke? (yes, I'm revealing my lack of knowledge about 4-strokes).

The TTR230 is air-cooled - does the porting increase the likelihood of overheating/seizure?

Are other modifications necessary to get the enhancement from the porting?

Does anyone have positive/negative experiences with having this service performed on their thumper?

Are there other or better ways to squeeze some more fun out of this playbike? I know it's not a racer and a trailbike (and a good one).

Any feedback would be appreciated, thanks ahead of time :thumbsup:

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You are foolish to waste your money on a 230 unless you really have some attachment to it.

Thats my opinion and im stickin to it.

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yeah really thats friggin retarde, i thught you were a racer looking for mor performance, but now i see you just have to much time on your hands

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Give the guy a break and answer his question. Yes you will notice gains throughout most of the RPM range. Head work is deff. worth the money. If you plan on keeping the bike, I would have the suspension worked out before any engine upgrades. But to answer your question yes you will see gains. Porting, and flowing will not make the bike run hotter. To my perspective it should run cooler.

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The only cons to porting your engine that I'm aware of are the cost (GOOD porting is almost always expensive) and the difficulty of finding a tuner with experience in porting a TTR230.

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Porting and a cam will make the bike a little more finky to alttitude changes and to be honest the 230 is pretty limited on what can be done to make the suspension better. It might be time to bump up to the TT 250 or WR250F. You can make any motor faster, but just how much do you want to spend?

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Thanks for the feedback thus far . . . well, maybe the first few replies left a bit to be desired, but there's a few in every crowd.

PRC charges $140 for the porting. Just to be specific, I'm not really trying to turn the 230 into a race bike, I just wanted a little more out of the bike to keep me happy and to have a little fun with the process. I do understand the limitations with trying to "mod" out a bike like the 230 - one can spend quite a bit of money and still feel like they fall short of their objective. But if I can spend <$200 and get a few more ponies without destroying the maintenance integrity of this machine it seems worth it.

I agree wholeheartedly about the suspension comments. I've got a mid-80s set of forks and triple clamps from a 250mx bike that I'll be installing. I'll end up with the whole front end (forks/clamps/wheel/caliper) when it's all said and done because axle size and caliper fit issues. (For the record, I've spent $60 for what I've got and will get the rest for another $40-50.)

Keep your thoughts coming!!

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If you decide to have the head ported, always ask if they flow the head! Any good port work will have the ability to flow the head and always pay for that as well. If the company/person does NOT have the equipment to measure head flow, walk away!

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Porting is serious business, especially on a 4banger. I don't know how good the mid 80's suspension is but I still don't think it owuld be worth it to port a 230. Once the suspension is better, the head is ported and your riping down the road, something else will show it's flaw, something like the frame possibly the rear drum brake will brake and you'll realize the money put in wasn't worth it. Wow, that was a run-on sentence. Also heavily modded playbikes don't hold their resale value real well. Keep it stockish, save your money, and you'll be better off. I've have been through this phase on my TTR125L. I'm glad I didn't modify it much at all. Resale was $100 less then what I paid for it.

Remember, the chain is only as strong as the weakest link.

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If you decide to have the head ported, always ask if they flow the head! Any good port work will have the ability to flow the head . . .

The description provided by PRC states, "All heads are flow bench tested for the best possible performance". I wondered how important this was - from your feedback I see that it is important and gives PRC a vote of confidence - thanks!

. . . heavily modded playbikes don't hold their resale value real well. Keep it stockish, save your money, and you'll be better off. . . Remember, the chain is only as strong as the weakest link.

Great stuff. My thoughts were to actually keep the TTR even when I end up with a different bike (still deciding but probably a KDX200, maybe even an XCW200 or 250). To your point, I'd best be sure I was going to keep the TTR before I change the forks.

Do you think the same is true with the porting? Would it decrease resale value?

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...PRC charges $140 for the porting...

:thumbsup: I've never seen porting services advertised for a price that low! If their work is decent, that's a bargin...

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Porting WILL alter the powerband. Opening up the ports to increase the cross sectional area will slow down the air velocity and result in some losses on the bottom and mid. You will get more on top, though. Adding material to the ports (either by epoxy or welding) will reduce the cross sectional area and will increase the flow velocity, increasing bottom to mid performance, at the expense of top end. There is really no free lunch if you're going to really "port" your head. What they may be talking about is just cleaning up the ports...that is, matching the port openings to the intake and exhaust manifolds, cleaning up casting flash and smoothing things out, polishing the exhaust and grit blasting the intake, and making the transitions in area a little smoother. In other words, making things like the engineers intended them to be, but the realities of rate production wouldn't allow them to be. This is good work to do with any motor, though you won't see huge performance gains.

Aftermarket cams are probably the easiest way to get more power, though they, too, will alter the powerband of your scooter. You don't have to pull the head to install them, either.

Big bore kits typically provide a consistent boost all across the RPM range, and really aren't that much more work than pulling your head to have it ported. The heavier piston associated with a big bore does, however, tend to slow down the revs a little, and they are pretty pricey.

One option that you did not mention to improve performance was a high compression piston. They are relatively cheap (less than porting or a cam, and quite a bit less than a big bore kit). Though depending on the combustion chamber design you may have to run premium or even race fuel to prevent pinging, the power increase across the board is impressive. Installing a high compression piston is about as much work as installing a big bore kit (so a little more than a port job), but the gains are impressive.

For what it's worth, I've done all of the above to my WR426 (now a 444). In order of bang for the buck, I would have to say the cams made the most "noticeable" difference, because they really altered the powerband, but in terms of really adding more power, the big bore kit (with a high comp piston) wins hands down. A high comp piston (before the big bore kit) added more power than the cams as well, but because it didn't really alter the delivery of the power (the powerband), it wasn't as noticeable until I realized how much faster I was riding through the sand washes, and that I was a gear taller climbing those really tough hills. As far as running race gas, I didn't have to until I put the whole combination...porting, hot cams, high comp piston, and big bore together. I'm not sure why that is...

Hope the info helps.

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It have to second the idea that the higher compression piston will get you the most bang for the buck.

A port cleanup (mentioned above) and a a "rev box" will let you run the engine faster at the expense of valve and valve spring life but may be a worthwhile upgrade - but I don't know how you ride so this would be a good upgrade if you continually hit the rev limiter looking for more power.

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Do you think the same is true with the porting? Would it decrease resale value?

Depends on the buyer of course, but if I see a bike that has an FMF pipe, cut up airbox, rims look beat up, chain rusty, etc I'm not going to buy it. You get the picture?

I bought a slightly used, very good ocndition '01 TTR125L in 2002 for 1400. I tried to keep it stock which was hard after seeing everyone say "your bike sucks, get an 85 or open up the airbox and put 85 parts on it, etc." There's n doubt I wanted to do that. So instead of beating up on the bike's engine, I just learned to lean it over more in corners, keep up the speed, velocity, momentum, whatever. I knew the bike pulled like crap, couldn't afford to be casing jumps, never dragged it, but never heavily modified it b/c I knew I would be selling it. Well, that I did. I cleaned it up nice and sold it for $1300 in 2006.

Ya know what, I am a better rider b/c I never heavily modified it.

just my $.02.

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. . . Aftermarket cams are probably the easiest way to get more power, though they, too, will alter the powerband of your scooter. . .

All of the info in your reply is very helpful, especially the notes concerning the cams and the high compression piston.

I follow you on porting changes: larger c/s area = more top end and vice versa. How does an aftermarket cam affect the powerband?

Also, will a high compression piston reduce reliability or increase wear/tear on the engine significantly?

Thanks for the feedback, great to hear from others direct experience. :thumbsup:

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Each cam will be a little different depending on manufacturer, application, etc. The Hot Cams for my 426 were billed as "increasing midrange and top end with little or no decrease in bottom end performance", which is exactly what they did. A little bit more of a mid-range hit, and a whole lot more on top. The other really noticeable difference was how quickly the bike revved...way better than stock.

From the hot cams website: http://www.hotcamsinc.com/catalog.asp#4019-1%%Yamaha%%TTR%20125%%1999-2005%%Stage%201%20Cam

Yamaha - TTR 125 - 1999-2005 Part Number: 4019-1

Description: Stage 1 Cam

Excellent midrange and top end power increase. Uses stock springs and rockers.

Price: $159.95

Based on that description, I would expect similar results on your TTR.

As far as durability is concerned, anything...cams, high compression piston, porting, big bore kit, will increase power. That means the entire engine and drive line will be worked harder than stock. Will it be enough to affect reliability? It hasn't been on my 426 (444). I have about 1500 miles on the build, and have had no problems. Do these mods increase maintenance requirements? You bet. I am careful to change the oil after EVERY day of riding, and the oil filter every other oil change. Air Filters? Every day. Chain adjustments? More frequent (though if you buy good quality chain and sprockets, they seem to last as long as with a stock motor). Will the clutch wear faster and will the fingers on the basket notch quicker? Sure. Will the bike be more sensitive to jetting? Yup. How about harder to start? Maybe. Mine is not. My son's WR250 with similar mods (except the big bore kit) is..at least for him. Do they run hotter? Not noticeably if the jetting is right. Again, though, I have to run race gas (VP C-12 at about 7 bucks a gallon). Is the performance gain worth the extra maintenance and fuel cost? Yup. Am I a pro level rider? Not by a long shot. I'm a fat, old, lazy rider. The extra power lets me carry a gear higher thru the tight twisties or gnarly uphills, and lets me get out of just about any situation with a little throttle, not a lot of clutch and/or panic shifting.

Something to consider, though, in planning your mods: The engine will only produce up to the first limiting factor. That is, if the intake is plugged up or the exhaust doesn't flow well, the engine mods will only produce more power up to the point that flow is restricted. On our WRs, we have removed the air box snorkels and "uncorked" the exhausts by removing the stock"pea shooter" baffles and adding YZ pipes with Pro Moto Billet 96 db Quiet Inserts. To get the most out of the engine mods discussed here, you would need to take some similar steps. For what it's worth, one of the folks in our riding group has a TTR-125 and put an FMF Q exhaust on and opened up the air box (I'm not sure how, I didn't see it with the seat off). The change was spectacular, though I'm sure more pricey than the Benjamin or Benjamin and Hamilton that putting in a high comp piston costs).

In spite of what a few others have stated on this thread, I don't view that as decreasing the value of the bike. I view that as mods that an informed enthusiast would make to increase performance and "fun factor". I also don't think those aftermarket mods increase the value of the bike significantly. With as many mods as my 426 has on it, the only one that adds any value is the California License Plate. What really matters is the condition of the bike. If the bike is clean and looks well maintained, you won't be hurting yourself in retail dollars.

Birdy

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My 02.

I think you are starting on an endless path of a minor change here and there to get more performance out of a machine that isn't designed for it. I would do all the basic things like uncorking the bike and making sure the jetting is spot on.

Everything else you try to do will be a compromise. Somewhat better power will require somewhat better brakes. Somewhat better power and brakes will require somewhat better suspension. It feeds on itself and at the end you still have a TTR30 that isn't worth any more than stock and might not be as reliable.

If you're planning on keeping the bike for a buddy bike or a backup, save the money you would have used for mods and get the bike you want. You will still have an excellent backup.

You could spend $5k on this bike and still not have as good of a machine as a stock 200xc 2 stroke or a stock CR250x or WR250.

ps: The KDX200 is a great bike and a late model example may be purchased for little more than trying to mod the TTR. :thumbsup:

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. . . To get the most out of the engine mods discussed here . . . one of the folks in our riding group has a TTR-125 and put an FMF Q exhaust on and opened up the air box (I'm not sure how, I didn't see it with the seat off). The change was spectacular. . .

Yeah, if you'll look back to the start of the thread I've been through these motions with impressive gains. I got a lot out of regearing as well.

I tend to agree with what you say about how keeping a bike clean relates to resell value. One poster suggested that a bike that looks like it's been ran to death with mods has a lower resell value is dead on, but to your point a bike that is well-maintained, with worthwhile mods, would certainly seem worth a little more than stock. The whole thing boils down to the eye of the future beholder.

You've put alot of effort into your postings - thanks a mil, I am definately more wiser for it.

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Great feedback, folks. 'Got several vantage points on this, but all-in-all I think it's reasonable to continue researching, especially about the high compression piston.

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