CRF50 carby angle adapter...???

[motoXXX]

ok we as you may no i have strenthened my frame and now my carby will not fit as it hits on where i strenthened it i made it so it would fit but i must of wlded it about out of place (ooops lol) now i need some ones help on here that can use a cnc machine or just someone that could make one of these out of billet or somthing so it would look half decent when its done and not a scabby jobb that i would do...

this is like what i would need done ,i would buy this one but the centre hole is way to big for a stock 50 as these are made for a lifan 140 i think...

im going to make one just out of metal as a template then i could send it to one of you guys like tormentandglory and bananaman i think it is that have or work at a machining shop with cnc machines etc etc then i could send you some cash awell for making it for me ??? all you would have todo is make it the same size etc etc as the one i made that i will send you???

would anyone be able to help me out here??? with making one or should i trya local machining shop or somthing???

i wont need as many holes as the ones in the pic i would just need 2 other sets so 4 holes that i can move my cable onto the angle so it will not hit my frame hes the frame problem im having

so if i could just put it on a slight angle by using one of those plates then everything would go back together great

thanks guys

 

[Cactus Jack]

You can buy adjustable intake manifolds that'll fit your head and they'll be cheaper than getting somebody else to make you an adaptor (which can raise the carb and cause even more problems) .... Just make sure you measure the width of the bolt spacings on your CRF head and ask the seller to make sure his manifold spacings are the same ...

Akunar has various manifolds ... and they have one of the types of spacers that you've shown (right down the bottom) but with a smaller centre bore (21 mm) ... The spacer you've shown is for big valve heads and has a near 27 mm centre bore ... March Hare Industries used to sell multi angle adaptors for CRF's and they had a small 21 mm centre bore ... What you have to watch with those things is that they are weak from all the holes drilled in 'em and can bend ... allowing your engine to suck air and fry ...

AKUNAR MOTORCYCLE MANIFOLDS

 

[Cactus Jack]

What size is the intake port in the head ? Stock 107 Loncins are 22 mm and stock XR75's are 20 mm (My XR's port is now 24 mm) ... I open the ports out to suit the manifold ... It's perfectly OK if the intake manifold is smaller than the head port as that blocks reversion pulses which prevents them from stuffing up the signal at the carb ... and reducing bottom end grunt ...

It looks to me like your intake manifold bore is too small for the carb outlet ?????

 

[Cactus Jack]

Mate ... they've detuned those things to the shirt house to suit little kiddies .... Honda has made the manifold smaller to give high velocity and block reverse flow ... and also to limit forward flow .... They've made everything small to slow the bikes down and also so they'll pull from a standing start in any gear ... I don't think you've got much to lose ... there's bugger all flow there anyway ...

As far as what you can do to improve performance ... It all depends on the valve sizes ... If the valves are 23 mm inlet/20 mm exhaust then you can do heaps to improve the power output ... The 15 mm intake port is good because when you port the head you only remove metal from the port roof and top side of the walls without touching the bottom ... then you'd do the same to the manifold where it enters the head but keep it 1 mm smaller all around to maintain strong bottom end torque to work with the auto clutch ... An XR75 or 80 Keihin carb (20 mm) should bring 'em to life coupled with a 23 to 25 mm I/D exhaust pipe ...

When tuners modified XR75's , they looked at what XL 100/125's were running then modified the 75's to run the same carb , port and pipe sizes ... with amazing results ...

 

[brucey_089]

oz 50 sells those adsapter things calll em and ask

 

[Cactus Jack]

thanks brucey...

cactus i was waiting to do my engine last after i do the flat seat and bar kti etc etc but im just gunna order a TB 88 kit (for stock head),ive got GENUINE keihn PC18 carb and a uni and a takegawa air filter and ive took the spark arrestor out of my pipe until i get an after market one so do you reakon the cheap setup i brought will be ok just untill later one down the track and also would you be keen if i sent you my head could you fix it up a little well CLEAN it up a little for me??? ill pay you for it???,not for a while but ill talk to you about that after i get the parts hear and settle them in and see how it goes???

thanks guys

Yes , I'll help you out with the stock CRF head ... no probs ... It'll be interesting to see what power increase can be extracted out of 'em ! The intake port and manifold would need to be opened out to the size of your PC18's outlet bore and the exhaust port opened out to suit your performance pipe ... But do you know that a 110 Loncin head will more than likely fit with a 52 mm bore and a high dome piston ? They have a 22 mm intake port and a 20 mm exhaust port as stock standard ... (E-22 head) and should work perfectly with an 88 cc kit ... XR80's run a PC20 (22 mm outlet bore) which I replace with a CB/SL/XL 100/125 22 mm Keihin (24 mm outlet bore) ... They work great EVEN on a ported 76 cc XR engine ... But horizontal engines probably haven't got the rpm capabilities of the XR engines (12,000 + rpm) ... A smaller carb would suit an auto horizontal engine better ...

 

[Cactus Jack]

As to the multi angle adaptors ... You can buy any one you like ... then get a bush pressed into the centre of it to reduce the size down to your stock intake port and intake manifold ... The bush can't possibly fall into the port either since it's too big ...

 

[Cactus Jack]

Yes it's a DEFINITE risk ... Don't use the stock thin paper intake gaskets with those adaptors ... I've seen how they bend firsthand when I modified my relos 110 Loncin (March Hare Industries adaptor) ... I had to use it against my better judgement because he was whinging that he had paid for it and wanted it on the engine ... We used one for THAT engine to raise the intake manifold so as to get enough clearance for the 22 mm Keihin carb and its deep float bowl ... I'd make one out of steel since you can get away with 6 to 10 mm thickness and it'll never bend ...

They bend where the two countersunk screws bolt the adaptor to the head ... The counter bores thin the metal section out and weaken the crap out of them ... You'd need to use silicone rubber type gaskets or sealant to allow for any gaps if they bent ... The March Hare adaptors have a rubber o-ring on the head side to get around the problem ... But that caused hassles for me as I had to open the centre of it out from 21 mm to 24 mm and went into the o-ring groove slightly due to the fact that the centre bore was out of whack with the centreline of the Loncin head port and intake manifold bore ... The adaptors were obviously made to suit CRF/XR 50 heads ...

You can most certainly lose power if you don't know what you are doing and hog a head out too big ... I only remove the absolute minimum amount of metal necessary to straighten out the flow ... if you lose too much velocity your bottom end grunt goes out the window ...

Whenever you increase port , carb or intake manifold bore sizes you are going to lose that strong kick off idle ... and there's nothing you can do about it ... I merely opened the stock Loncin 120's intake manifold out from 18 mm to match it to the stock head port and carb outlet and it lost it's off idle kick ... but it was a lot smoother and less abrupt which is better for the transmission ... They run everything small so that manual engines won't stall as easily for kids if they let the clutch out too quickly without increasing the revs or synchronising the clutch smoothly ...

Of course ported engines go heaps better when you twist the loud handle hard with the engine revving and use good clutch synchronisation and gear selection plus the right final drive ratio ... You can buy higher stall speed clutch weights and springs for CRF auto clutches to allow the engine to rev higher on take off ...

Here's a pic of Loncin intake manifolds .... (Left) Stocker ~ 18 mm bore ... (centre) Port matched to stock carb and head port ~ 21 mm bore and (right) matched to ported head and 22 mm Keihin ... 24 mm bore ... Loncins are pretty close to an exact CRF engine copy and have the exact same cylinder stud spacings ...

 

[Cactus Jack]

What's hitting the frame ? The manifold or the carb ? IF it's just the carb you can space it back further by making a thicker carb to manifold insulator ...

 

[wogtaz ryder]

looks like it would do the job! nice work .. i think it would anyway lol

and cactus i have been thinking of putting my 107cc head on my crf50 with 88 bore kit and stock head the studs are the same pattern but im not sure if it will work? what could be the worst that would happen? my piston isnt really a high piston i dont think so it shouldnt hit?

 

[Cactus Jack]

Good ... it shows that you're thinking and having a go and that your father has good fabricating and welding skills which should rub off onto you ...
I know exactly what you had to do since years ago I had to make an adaptor out of steel to fit a 22 mm Keihin to a later model XR intake ... Later model XR's have the manifold mount bolts level on the head and the carb mount but earlier heads had both theirs tilted at an angle ... the stock 20 mm Keihin carb itself had a tilted flange ...

So I marked the carb gasket out onto 6 mm steel plate , then rotated it to the degrees of the tilt angle and marked it out again with the centre bore holes aligned ... All I had to do then was drill the centre bore to 24 mm then drill and tap the 4 bolt holes ... The end result was a carb spacer that had two studs sticking out of one side and the other two sticking out of the other side ... I chamfered the holes in the plate , screwed the studs in then welded them and ground them flush ... The end result looked great and has worked perfectly right up 'til this day ....

Using a later model Honda XR75 straight , long intake manifold was even better than buying a special aftermarket manifold (which I simply couldn't find at the time) because the bore was a lot smaller than 24 mm and that allowed me to raise the intake port upwards and move it over to the right on the earlier model head for an even straighter gas flow ... Along with my port job and various other mods the engine hammered ...

Another thing you could possibly do is .... Neatly and cleanly hacksaw your stock manifold off at the head mounting flange , rotate the top part until the carb clears . Mark it in 4 places , then get someone to weld it back on ...

It's also possible that a stock Loncin or other chinese intake manifold might be angled more than the stock CRF one to clear the frame ?????

 

[Cactus Jack]

Your adaptor looks really good and the metal looks pretty thick ... IF you have problems all you'd need to do is add another plate of the same thickness ...

Smear the gasket paper with silicone gasket both sides (like you're greasing 'em) ... then let them partially dry and stick them to the metal plate then attach the adaptor to the head but only just nip the bolts up ... lightly coat the manifold flange face with WD40 or a thin film of oil to stop the silicone from sticking to it , then lightly bolt that on and let the silicone dry a bit ... That way when you finally tighten them down when things are dry ... the silicone will be thick enough to seal any leaks plus silicone withstands heat ...

When you get around to running the engine ... check that the spark plug isn't grey or white ...

As it is , does everything feel solid with no movement when tightened down ???

I'll have to show some pics of my adaptor and contraptions ... When there's nothing available to buy you have do things Mc Guyver style ... but I'd stop short of welding conrods back together with a car battery as a welder and coat hanger wire as welding rods ....

 

[Cactus Jack]

looks like it would do the job! nice work .. i think it would anyway lol

and cactus i have been thinking of putting my 107cc head on my crf50 with 88 bore kit and stock head the studs are the same pattern but im not sure if it will work? what could be the worst that would happen? my piston isnt really a high piston i dont think so it shouldnt hit?

Bare Loncin 107 heads are 91 mm tall (minus finned top cover) ... IF the head is taller than a stock CRF head you'd probably need to use longer cylinder studs ... Your piston wouldn't hit the head because they have a squish band around the outside of the combustion chamber ...

They use the short chinese 3 bolt cam (same length as GPX Jialings) but without any anti kick back mech ...and a 3 bolt 32 tooth cam sprocket ...

So you'd have to make sure you use a cam sprocket with the same amount of teeth as a stock CRF engine ...

The worst that could happen is that you'll gain more power cheaply ...

 

[wogtaz ryder]

hmmmm i would really like to try it , so the sprocket on my 110 is 3 bolts and the 50 is 2 bolts were would i be able to get one that will fit , thats if the 110 is the same amount of teeth as the 50? mmmmm power mmmm cheap

so if the cam sprockets are same teeth you rekon it's safe enough to give it a go?

 

[Cactus Jack]

Yes .... You'd only need to change the Loncin sprocket IF your CRF has a 28 tooth cam sprocket and in that case you could use a Lifan 140 cam sprocket ...

I'd try a CRF 50 head gasket up to the the 107's head to make sure the oil drain back hole is in the right place first ... The 107 runs a 52.6 mm bore ...

Another thing to check first would be the distance from the camshaft centre line to the head deck gasket face ... IF they're about the same distance and the gaskets check out ... then everything should be OK ... You'd probably need to check piston to valve clearances but if all the rest checks out , they should be OK too ....

Think of it all as a learning experience ...

 

[wogtaz ryder]

yer thats what i want to do it for to learn .. but i just dont no about experimenting on my Honda engine lol

and!! im not even sure if it is a loncin? it has the same stud pattern as crf50 and it is about ...... maybe more then 4 years old , all down gears with clutch and originally electric start , would it matter? as long as it all lines up etc and says VM on the side

thanks for the help i mite give it a go when i have some time on me hands

sorry about your thread motoxxx lol



Thanks

 

[Cactus Jack]

well thanks cactus ,much appreciate it mate,the metal is 3mm i think sheet metal,its the stuff i used to brace the frame so do you think this should be safe enough???

the worst thing that can happen is that i fry the piston yeh???,well thats not so bad then id have an excuse to get an even better bore kit haha.

well ill give it a try

The idea is to not fry anything other than food ... ... 3 mm is a bit thin but as I said , all you need to do is double up on it ... Be very generous with that silicone sealant and make thicker gaskets out of proper gasket paper ... and check that plug colour out ...

 

[Cactus Jack]

Thicker metal would be better ...

 

[unit_mx]

You need to space the tank 1" higher to clear the larger carb on stock frames , its like that with all bigger carbs. Five-o make spacers only like $20 or DIY

 

[wogtaz ryder]

nope my five0 frame has tank risers .. i reckon it looks better