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GoldenMotor.com

Toothy

New Member
Mar 25, 2014
181
1
0
San Diego
Well gang I finally got my chain set up right. I ended up putting the tensioner on the bicycle chain and it works like a charm. My next challenge is to fix the 4 stroking. It happens in the lower RPM’s. I haven’t messed with the needle as yet and was planning on changing jets. I’m at sea level and was wondering what size to try first. Do I go up or down? I was tempted to try soldering a copper wire in the jet but not sure how to…



 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
No need to solder wire into the jet. Just solder the orifice closed and redrill. be sure to confirm the original size of the jet then go one drill bit size smaller.
You might not get it on the first attempt. It often takes some experimentation to find the right size.
Whatever, you need to know that you need at least about 100 miles on the engine to really know what it needs. A new engine with less than 100 miles will never perform as good as one with some miles under its belt. Actually I like to see closer to 200 miles on an engine to really determine which way to go with the fuel/air mix.

Another thing to keep in mind is that the 'C' clip position has no effect on WOT, wide open throttle. The needle that the 'C' clip is on only controls fuel flow below about 3/4 throttle. Anything above that is determined by jet size.

Tom
 

Toothy

New Member
Mar 25, 2014
181
1
0
San Diego
Thanks 2door, the 4 stroking seems to happen in the lower rpm range. I guess I'll buy some jets and fine tune from there.
 

crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
if you look up 4-stroking in youtube, you may find the vid that shows racing chainsaws that are set up to pop & 4-stoke near idle for good torque response, then they 2-stroke nicely at higher revs

old rule of thumb is rich for power lean for speed
 

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
Thanks.....I live in a hilly area so low end power would be preferred.
Toms advice is spot on the same as I do mine, but if you do decide to just buy multiple jets, www.treatland.tv is the best place I know of to get the 5mm Dellorto jets, all of my NT carbs I've checked hada .70 jet stock so I'd suggest probably getting #68 and smaller.

Just seems crazy to me to but jets when its so. Heap and easy to solder the one jet until its perfect, no waisted $'s on jets you'll never use.. just my opinion on the matter.

Map
 

Toothy

New Member
Mar 25, 2014
181
1
0
San Diego
Toms advice is spot on the same as I do mine, but if you do decide to just buy multiple jets, www.treatland.tv is the best place I know of to get the 5mm Dellorto jets, all of my NT carbs I've checked hada .70 jet stock so I'd suggest probably getting #68 and smaller.

Just seems crazy to me to but jets when its so. Heap and easy to solder the one jet until its perfect, no waisted $'s on jets you'll never use.. just my opinion on the matter.

Map
Map / 2 door you make a lot of sense, can you by the bits a home depo store or somewhere more specialized?
Thanks!
 

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
22
0
memphis Tn
I just ordered a set today from Home Depot. They have them in the online catalog.
Qty
Ordered Internet # Product Description Unit
Price Amount
1 204586187 #61 - #80 High Speed Steel Wire Gauge Drill Bit Metal Box Set (Set of 20)
 

Theon

New Member
Jan 20, 2014
1,440
6
0
FNQ Australia
Where is your needle set?
Sounds to me as though you may need to lower the needle, raise the clip.
For hills rich needle is better.
 

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
Map / 2 door you make a lot of sense, can you by the bits a home depo store or somewhere more specialized?
Thanks!
www.widgetsupply.com

Search drill bits and get a set of the wire gauge bits that measure in size from 80-61 and you need a pin vise to chuck the bit in which is cheap there on the site, around $10 for the whole set up and you'll have what you need to fine tune your carb.

My elevation here is 1240' above sea level and either a jet frilled with the #72 or #73 wire gauge bit tunes my NT carbs good for my set up, I'd probably start with a #72 since its common to have a #70 as the stock jet size, with wire gauge bits the larger the number the smaller the bit, a #73 is smaller than a #70 and so on.

Map
 

Toothy

New Member
Mar 25, 2014
181
1
0
San Diego
Thanks the info.....really great stuff. I went for a ride yesterday and It's been a lot of fun. The bike is running very smoothly with little vibration. I may be expecting too much but it would be great if the initial throttle back was as smooth as the rest PLUS from my understanding with 4 stroking you are loosing power.
 

Theon

New Member
Jan 20, 2014
1,440
6
0
FNQ Australia
Yes sorry bad explanation,
If it's 4 stroking in the low to mid drop the needle a notch, however for hill climbing a little rich is good.
I find clip on the second notch from the top is usually best. Should 4 stroke when you back off.
 

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
Yes second notch from the top is what most all of us have found to work the best and then adjust jet size form there after you have air filter you plan to run on carb and you have exhaust you plan to run set up on engine.

Map
dnut
 

xseler

Well-Known Member
Apr 14, 2013
2,886
151
63
OKC, OK
I just ordered a set today from Home Depot. They have them in the online catalog.
Qty
Ordered Internet # Product Description Unit
Price Amount
1 204586187 #61 - #80 High Speed Steel Wire Gauge Drill Bit Metal Box Set (Set of 20)

Thank you for helping to keep me employed!! (^)
 

Toothy

New Member
Mar 25, 2014
181
1
0
San Diego
So I moved it up from the middle notch to #2 on the needle. The idle went way up with some vibration, had a screwdriver so no big deal. Can't tell if it is better or not. I'll mess with the jet next.
 

SuperDave

Member
Sep 24, 2011
179
0
16
Panama City Beach, Fl. USA
If your gonna solder & redrill to go leaner, select a drill bit 3 sizes smaller than what it has now to start with. That way you can go bigger than what you already drilled out without having to resolder it every time if 3 sizes is too lean. Otherwise you might spend all day dialing it in.
 

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
Thats another good way to do it, I actually don't re-solder mine because there is enough solder in jet when I do mine that all I need to do is just heat the jet a bit and solder will melt and fill hole and then I redrill, but doing it the way Dave suggested will work great also and there will be no need to reheat the jet.

Best wishes, hope you get it running like a scalded ape asap..

Map
.wee.