16 replies to this topic

[millerme]

i just bought a tlr 200 and want to know if any one has put a head from a xr 200 as it has bigger valves and also want to know how good the wes exhaust`s are

[GrahamJayzee]

Hi,

Not so sure I'd want bigger valves on a trials bike. Larger valves help get more fuel/ air mix in and more exhaust gases out. This has the effect of improving power towards the top end of the power curve at the expense of the bottom end. It will also require a larger carb opening and different exhaust. It may make the bike better for green laning (I say may...), but is likely to adversly affect it's usefullness as a trials bike.

I could (and often am) be wrong though...

Graham

[1oldbanjo]

GrahamJayzee, on 07 September 2011 - 12:58 PM, said:

Hi,

Not so sure I'd want bigger valves on a trials bike. Larger valves help get more fuel/ air mix in and more exhaust gases out. This has the effect of improving power towards the top end of the power curve at the expense of the bottom end. It will also require a larger carb opening and different exhaust. It may make the bike better for green laning (I say may...), but is likely to adversly affect it's usefullness as a trials bike.

I could (and often am) be wrong though...

Graham

Yep.......I agree. Don't put a Ferrari head on your John Deere! Seriously - the small valves and intake ports and carb keep the air velocity up at lower rpm's and make throttle response crisp. If you put parts with bigger holes on it....the velocity will go down at low rpms and things will get sluggish until you rev the motor up. There is a reason the engineers put smaller valves in the engine....they know what they were doing when they designed it.

[tlrmark]

Hi one of the best modifications you can make on the tlr, the stock valve sizes are tiny on the tlr and chokes the performance. I have done this modification on three 200's and highly reccomend it for all levels of riders. The compression ratio should also be raised in my opinion, these mods are more important than expensive exhaust systems. My two cents. Cheers Mark

[mattylad]

Dont forget that the XR cam profile is also different.
tlr mark did you also change the cam?

[tlrmark]

Hi no dont use the xr cam it is too radical for trials. My favouite cam for trials or enduros for that matter in the 200 two valve engine is the atc200e cam very smooth and mild. Wiesco 10.1 piston is also highly recommended or stock Honda xr200 piston which is also 10.1 but very pricey and is a cast piston not forged like wiesco. Dont forget the xr is not very radical stock, the xr200 valves are the same size as the 1979 and up xl125 trailbike, the 1979 and up cb125 roadbike and the 1979 and up xl185 trailbike very mild mannered machines all. The xl 185 cam some people like for trials it is halfway between the atc cam and the xr cam in performance but as I said I much prefer the mild atc cam it is similar to the stock tlr cam. Most shops like classic trials in england or powroll in usa fit the xr intake valve in the tlr head as a standard upgrade at a minimum. Much easier to use a used xl185 head or used xr200 head off ebay. Hope that helps.

[millerme]

thanks all for your advice i think i will be doing so engine mods, And will build my own exhaust system rather than buy one for £170.00 as i can use the TIG welder in work to weld aluminium will let you know in a few months time how i got on

[quickmick25]

TLRMARK,

You only changed the inlet vakve and not the exhaust valve for them from XR200??

[tlrmark]

quickmick25, on 11 December 2011 - 07:36 PM, said:

TLRMARK,

You only changed the inlet vakve and not the exhaust valve for them from XR200??

Hi I myself actually use the entire xr200 cylinder head, which of course uses both the intake and exhaust larger sized valves. For me this is cheaper and easier than new valve seats etc. which I dont have the tools for. Used cylinder heads on ebay can be had for 50.00, of course they will probably need new valves which are not expensive. Also dont forget the XL185, xr200r single shock, xr200 twin shock, atc200e, atc200m, and atc200s are all identical cyl. heads not counting paint colour. You must get the rocker cover with the cylinder head as Honda line bores both parts together for the cam jounals. With a wiesco piston for the xr200 10.1 instead of the stock tlr 8.1 and the larger valves it makes a serious increase in power which the anemic tlr can really use, it doesent at all make it in any way harder to ride or give it a narrower mx type powerband, just much more low end and mid range power, very smooth. Classic trial shop in england and Powroll in the states as well as many more shops over here do the larger intake valve modification no idea what it costs.

[bashplate]

hi TLRMARK, interesting stuff on the heads and cams. was just wondering if you had ever tried advancing the cam ( 6 degrees ) which is supposed to tilt the torque curve towards the bottom of rev range. was hoping to try this on my 200 special which is based on a XL200R. cheers.

[tlrmark]

bashplate, on 12 December 2011 - 02:26 AM, said:

hi TLRMARK, interesting stuff on the heads and cams. was just wondering if you had ever tried advancing the cam ( 6 degrees ) which is supposed to tilt the torque curve towards the bottom of rev range. was hoping to try this on my 200 special which is based on a XL200R. cheers.

I have always meant to try this but never got around to trying it. Chris at classic trial in england does play around with this and reports positive results, check his website. I have tried every single different camshaft honda use in these two valve 185/200 engines and much prefer the atc200 cam very smooth power with more power off idle and then falling flat at high rpm, just like any modern trials engine power characteristics. My second favourite cam is the xl185/xl200 cam which is kind of a medium type power. The xr200 cam doesnt work for trials a big loss of power off idle and then comes on hard in the mid range, makes it hard to control. My latest mod is trying a Mikuni TM 24 carburetor which is a flat slide. Very very happy with this after 6 months of dialing in the jetting.

[bashplate]

thanks for that mark. my bike is still running the xl cam and is good....but could just do with a bit more grunt at the very bottom when trickling along on rough ground.would proberbly get round it by dropping another touth to 9 on the front, but would be chewing through the swing arm slider a bit more!!! i'm still using the standard 26mm? oval carb, which has very nice power once off the idle. think i may try the cam advance mod if i can't find the atv cam, will report back if and when i get some results, biggest problem is finding enough spare time.....though i do love tinkering

[quickmick25]

tlrmark, on 12 December 2011 - 02:02 AM, said:

Hi I myself actually use the entire xr200 cylinder head, which of course uses both the intake and exhaust larger sized valves. For me this is cheaper and easier than new valve seats etc. which I dont have the tools for. Used cylinder heads on ebay can be had for 50.00, of course they will probably need new valves which are not expensive. Also dont forget the XL185, xr200r single shock, xr200 twin shock, atc200e, atc200m, and atc200s are all identical cyl. heads not counting paint colour. You must get the rocker cover with the cylinder head as Honda line bores both parts together for the cam jounals. With a wiesco piston for the xr200 10.1 instead of the stock tlr 8.1 and the larger valves it makes a serious increase in power which the anemic tlr can really use, it doesent at all make it in any way harder to ride or give it a narrower mx type powerband, just much more low end and mid range power, very smooth. Classic trial shop in england and Powroll in the states as well as many more shops over here do the larger intake valve modification no idea what it costs.

Hi,

Thanks for your informations

Is it possible to keep the TLR ignition on my bike with all this big valve heads.Is only the ATC200X different?

Just had alook on Wiseco hompage http://wiseco.com/ProductSearch.aspx , 67mm and 204cc would be nice.

Could i still use a TLR head gasket?

Thanks,
Jeff

Edited by quickmick25, 12 December 2011 - 03:58 PM.

[tlrmark]

quickmick25, on 12 December 2011 - 02:03 PM, said:

Hi,

Thanks for your informations

Is it possible to keep the TLR ignition on my bike with all this big valve heads.Is only the ATC200X different?

Just had alook on Wiseco hompage http://wiseco.com/ProductSearch.aspx , 67mm and 204cc would be nice.

Could i still use a TLR head gasket?

Thanks,
Jeff

Hi yes it is easiest to use your stock camshaft and ignition setup, the xr ignition is triggered off the end of the cam and would be more work to use. I use a 66.5 wiesco piston and even then the cylinder wall is getting pretty thin. Honda never offered oversizes on the 200 sized engines (195 cc actual) as they always said it was too marginal to go any bigger. I believe the increase in compression ratio is more important and delivers greater performance than the larger valves, it will give the engine more snap right off idle. Yes no problem using the stock 200 head gasket, I would stick with 66 mm or maybe 66.5 mm piston size though. If you do tear the engine down to do these modifications be sure to use new valve seals as these harden with age and are a major source of oil consumption, use genuine Honda valve seals only aftermarket are garbage, I prefer genuine Honda gaskets as well. I would replace the cam chain as well while it is apart, for these I prefer aftermarket half the price of Honda and much higher quality Tsubaki or DID. No cheap chinese junk. The engine will last the rest of your life then, with frequent oil changes. These mods will transform the bike and not compromise reliability. Best of Luck Oh almost forgot the use of atc200x parts you asked about, there is no real advantgage to the atc200x cylinder head valve size is the same as atc 200e, atc200m, atc200s, xl185, xl200, and xr200. The disadvantage of the 200x cylinder head is that it is the only 200 head you cannot use the stock decompression starting system with, it has no greater fin area on the head but the rocker cover is slightly more finned for cooling. The atc200x cylinder is a completely different story though, very desieable part and searched the world over by trials and enduro competitors. No longer sold new through Honda and so sought after scammers on american ebay routinely try to sell regular 200 cylinders as 200x parts. It has much greater fin area and really does make a big difference in cooling the engine espescially for trials where the bike is stationary a lot or moveing fairly slowly a lot. I use the atc200x cylinder and cylinder head as I dont use the decompression system, like I said above though the x head doesnt really make any difference though. There is a lot of confusion out there amongst buyers and sellers over these x parts, three years only were they made 1983, 1984 and 1985. The 1986 and up atc 200 and four wheelers TRX200 are a completely different engine and nothing off these engines fit the earlier ones.

Edited by tlrmark, 13 December 2011 - 01:51 AM.

[tlrmark]

bashplate, on 12 December 2011 - 07:27 AM, said:

thanks for that mark. my bike is still running the xl cam and is good....but could just do with a bit more grunt at the very bottom when trickling along on rough ground.would proberbly get round it by dropping another touth to 9 on the front, but would be chewing through the swing arm slider a bit more!!! i'm still using the standard 26mm? oval carb, which has very nice power once off the idle. think i may try the cam advance mod if i can't find the atv cam, will report back if and when i get some results, biggest problem is finding enough spare time.....though i do love tinkering

I seeIn believe the XL 200 uses a 24 mm carb, I have seen it listed as haveing a 24 in some genuine Honda manuals and I have also seen it listed as a 26 in aftermarket manuals Clymer etc. Of course the XL185 is the 24 for sure and the XL 200 is exactly the same engine (state of tune) except for the difference in displacement. XL125 is 24, TLR200 is 22, XR200 is 26, XR 185 is 26 they are very hard to measure because of the oval venturi as you noted. For gearing I use 10 and 50, I know in england 9 and 44 is most commonly used.